Hi,
I am upgrading basically everything in my computer except the sound card. With a 64-bit processor, I need to get a new version of Windows. In your opinions, which is better, XP64 or Vista? I will be using the system for high-end games, audio/synthesizer work, and maybe programming and 3D graphics.
I want advice in terms of speed, stability, effeciency of system resources (I head Vista takes a lot of memory just to run), HD space for the basic install, backwards compatibility w/ 32-bit programs, and how big the "idiot-factor" is -- how much it wants to make system settings for you without telling you or give you the ability to change it.

Assume that I would get the highest-level (besides server) version of the OS and that money is not an issue.

Uhm ... sorry, this is _Linux_ questions. You won't get reliable answers about windows issues here.
But then, think .... many of the "high-end" or market-niche programs - unless open source - will not be compiled yet for 64bit, so look around if you get compatible programs and in particular signed drivers for 64bit windows (unsigned drivers may end up denied by windows,
where "unsigned" means the driver maker has not paid for signing, nothing more).
Btw., unless you have significantly more than 3 GB of RAM (talking about 8G and more which your mainboard may support or not), and your programs can make use of the extra ram, you won't notice a speed increase except for numbercrunching apps.
In fact, for high end games you are best with a dedicated game console.
For programming, audio work and 3D modelling you'll get all apps for free - not pirated - with linux.

You will have problems with both.

There is not a lot of 64 bit software out there yet, and M$ has broken a lot of compatibility with their move to 64 bit.

If those are the choices, go with XP, IMO. But you'll probably also want to install VirtualPC and load a 32 bit XP into it so that you can use existing software.

Aren't most programs backwards compatible with 32-bit?

In a word, "no".

Some of them are, of course, but many (probably most) are not.

32 bit programs have been out there for a long time now, and many of them have their roots in 16 bit code. An awful lot of commonly used programs depend upon old 16 bit dlls or even have old 16 bit code in them.

I include in that list my very own commercial application, which has a strong dependence on the 16 bit subsystem.

But, with the move to 64 bit, M$ has dropped all support for this older code. This is forcing everyone (including me) to modernize old, reliable, core code. It is happening, but very slowly. You'll see a lot of compatibility problems when you try to run 64 bit Windows.

Since you have many compelling business needs at-work in this decision, I advise you to set up a very carefully defined actual test-case.

Without jeopardizing anything about "how you make your $m$o$n$e$y$ now," see for yourself. If that involves purchasing an entirely new computer... do so. Keep the receipt. You can return it. No, I'm not kidding.

You're right---perhaps OP should try http://windowsquestions.org ............

Yes, we DO help with Windows, but we're better with Linux. (Well maybe some of us are.......)

I know, but I'm too lazy to create an account on another site just for one question.

You do *not* need a 64-bit OS for the AMD64 and Intel EMT64 families of CPU. Those machines are quite happy to execute code which is compatible with the Pentium family of processors. Availability of 64-bit drivers and native 64-bit software is still a huge issue (even though MS claim that 64-bit driver availability is no longer an issue - yeah, and elephants are green). For example, good luck finding any 64-bit Adobe software or a 64-bit version of Skype. However, if the operating system can also provide a 32-bit system call interface (as Linux does), then it is possible to continue installing and using 32-bit software - after all, that is one of the biggest deals with the AMD64 design.

What you need to spend time working on:
1. what hardware will you be using and how well is it currently supported on 32 and 64-bit versions of XP and Visduh?
2. how much memory do you have; do the 32-bit operating systems limit the amount of RAM you can access?

Eventually I think the world of home computer users will switch to 64-bit systems just as it switched from predominantly 8/16-bit CPUs to 32-bit CPUs, but it may take a few more years yet. I've been using a variety of 64-bit systems since 1994 so such systems have existed for at least 15 years (and were common and fairly popular for users in my profession), but for MS users I would recommend waiting a few more years before jumping in.

I have Vista home premium installed and I love it. I find Vista to be more responsive then XP on anything I may use.

Resource usage does not seem bad to me. I have 4gigs of ram and like Linux it may look like it is using it all but is reserved for cache. I like Vista very much.

I actually installed XP on this new rig when it first came in and was not anywhere near impressed. Vista brought it to life.

I have 32bit on my 5400+BE BTW. This machine SCREAMS!

Hmmmm in deed. The main problem is not vista or xp it's 64 bits in general.

Even on linux there are issues with going purely 64 bit. Mainly this includes any commercial software (the little that there is including games) and specialized speed enhanced programs with assembly code (of which I have run into issues with emulators) or programs like openoffice that are just to complicated for a casual user to install (not to mention have issues with java dependencies when in 64 bit).

Back to windows. Seeing that vista has been out long enough to get stability fixes. any software vendor planning on moving to 64 bit code will more than likely have more support for vista rather than xp64. XP64 should remain in the realm of data bases and servers that were ahead of the game.

Really though what is the advantage of 64 bits? Faster calculations of code that were previously represented as 64 bits but with 32 bit based code. Higher precession of numbers. Ungodly amounts of theoretically capable ram (as long as your board and bios supports it). And so I'm told faster video editing at least until the standard color depth changes.

I would definitely follow the previously mentioned advice. RESEARCH which programs you want to use and find out if all the ones you MUST have use 64 bit code. Otherwise you will just end up being frustrated when you get something that really doesn't work right because it's 32bit code pseudoly running in a 64 bit environment at the cost of speed, performance, stability, or at all.

I don't believe there's any pseudo about it. AMD64 (x86-64) supports 32 bit code.

From: http://en.wikipedia.org/wiki/X86-64
I'm starting to wonder if I should convert, after all.

I wasn't talking about the instruction set. I was talking about the capability of the operating system. If the system is compiled only for the 32 bit instruction set then any program specifically compiled for 64 bit will not run unless absolutely every dependency is compiled into the program and vice versa. From what I have heard with vista64 and xp64 is that they are compiled for 64 bit instruction set but they do something funky to support 32 bit mode. At least on linux, to support both 64 and 32 bit you need to have duplicate libraries for both instruction sets assuming that you want to install pre-compiled binaries that rely upon external common libraries. I know plenty of laptops that have vista32 on them even though the processor it self is 64bit and that IS possible because the processor supports both instruction sets. I don't know the details and I'm sure I'm missing something. But anyway! 32bit windows binaries will almost absolutely run slower on vista64 and xp64 than they will on 32 bit verities for the very reason of how they support 32 bit code. It's easy to assume that other complications may arise.

Does that mean that a 64-bit program will be slower on a 32-bit OS?
Wait, will they even run?
I find this all very confusing.

Look it up?

I was just spitting out fragments of what I have read and I can not vouch for the 100% validity of what I have said thus far.