I am going to build a 64 bit box based on the amd athlon 3000+ and asus a8v deluxe mainboard with via chipset. I understand from what I have read that 64 bit apps are now more common, however, there may be a time where software is available only in 32 bit form so I might want to revert to a 32 bit os. Can a 32 bit os run on 64 bit hardware? I intend to use the new box for gaming.

Yes, you can run a 32 bit os on a 64 bit processor. If you weren't able to, all the windows users that have a 64 bit processor would be sol with the lack of software for 64 bit in microsoft. The same holds true for linux programs.

the 64 bit OS is optimized to use the capabilities of the 64 bit processor and will therefore be faster but the 32 will still work and will also have more applications that run on it

At the moment, I am using a 32-bit verion of Linux on my AMD Athlon 64 3800+ computer. I am running Slackware 10.2 which is a 32-bit version of Linux. I also have the AMD-64 version of Ubuntu installed on this same computer and can boot up into that instead, if I prefer. In addition, I also have Windows 2000 and PC-DOS 2000 installed on seperate partions. I assume that Windows 2000 is a 32-bit OS and that PC-DOS 2000 is probably a 16-bit OS. I boot up into DOS on my AMD Athlon 64 every once in I while so that I can have that retro experience of playing a few old 16-bit (or whatever) arcade games from the late 1980s and early 1990s. Of course, I can also run the old 16-bit DOS games inside the free DOS-BOX program running under Linux. This is a computer that I built myself back in early 2005 and it can boot up in any of those operating systems. The one thing that I am not actually sure about is if there are any problems with randomly mixing both 64 and 32-bit software within either a 32 or 64-bit version of Linux. Perhaps someone else could answer that question.

I use this as a desktop computer at home and it is very responsive and fast when running either the 32-bit or 64-bit versions of Linux. The AMD-64 places the memory controller directly the CPU and if I understand correctly, that reduces latency and might possibly help explain why this computer has a quick responsive feel. I am not an expert, but, That benefit would presumably still apply when running either a 32 or 64-bit operating system. If I remember correctly, I once read that the AMD-64 was intentionally designed to perform well with either 32 or 64-bit software or operating systems. I am not a gamer and am not very familiar with what a gamers exact needs would be (other than good performance and video). My main goal was to build an ultra-quiet (but powerful) computer from components that were all compatible with both Linux and Windows.

When using a 32-bit version of Linux there is still at least one AMD-Athon 64 specific feature that I use under Linux. It is the AMD-64 "Cool'n' Quiet" feature. The Cool'n'Quiet feature is a power management technology which automatically throttles pack the processor to reduce power consumption and temperature when the the processor is idle. I keep my computer plugged into a small Watt meter so that I can tell how much power it is using at any given moment. That is a feature than can be can me enabled in either the 32 or 64-bit versions of Linux (at least with a 2.6 kernel anyway).

To protect delicate electronic components from static electricity, when you build your computer, it would probably be best not to do it on a carpeted floor. I also wore a static-protection wrist strap.

In that case, I am going to go with a dual-boot box. Rick485, how were you able to get so many partitions set up on your pc? Did you use fdisk? I heard somewhere that if windows is going to be on a multiboot drive, that it would be installed first, then the linux os.

Yes, install windows first and then linux. Windows boot loader doesn't like anything but windows os's but the linux boot loader will recognize the linux as well as the windows os's.

hi sirius57,
I think its good to install 32bit os on 64 bit machine architecture as though you said most apps are in 64 bit now. But the major problem i faced on 64 bit machine with 64 bit OS is that lack of some required apps in 64 bit that leads me to install 32 bit app on 64 bit some worked well but some changed lib path to 32 bit libraries. e.g Firefox plugins are not available in 64 bit still.
and some newer 64 bit apps got are now not installing at all. I need to specify /usr/lib64 explicitly so that new application never go to 32 bit library in /usr/lib
so in an all currenlty until 64 bit apps got maturity i better would like to stick 32 bit os