Oi. Alright the story is I had vista on my new acer laptop which it came preloaded with. I was up at college for several weeks and didn't want to mess around with the laptop till I got home for a little just in case something went wrong. I have a Acer Aspire 5100 which isnt bad for the $500 I spent on it. I have a decent amount of linux experience.
Anyway Im wondering will it be better to install the 64 bit version seeing as it in a AMD 64? Will it make a huge differnce in performance and what about 32 bit applications? Also I am wondering if I should take a whack at Gentoo. I was asking around and half of my friends say yes and the others say no. Will it be worth it? I am just not sure about compiling everything from scratch.
A few of my main questions are about the 64 bit stuff is I never had a 64 bit machine so this is a little new to me. What is the major difference in the programs and such. Like if I install a 64 bit OS but run a 32 bit application? Ect. Any answers/links are greatly appreciated.
Thank you.


PS
Currently I just threw Ubuntu on it for the ease and just to get Vista off here. I am probably going to get rid of it though. Any suggestions are good. I might use Slackware like I use on my desktop box.

Some distro's like openSuSE have a biarch architecture. SuSE installs the 32 bit version of firefox by default, for example. This allows you to run 32 bit extensions.
The biggest advantage to running a 64 bit distro is being able to install more memory.

I am probably not going to upgrade the memory much more than it is. Right now it is at 512mb but maybe I will double it.

Then you'll be fine with a 32-bit version of any distro. As jschiwal said, the biggest advantage of 64-bit is the ability to use over 4GB of memory.

alright that sounds good to me. I have another question. Is gentoo worth the hassle?

Personally, I didn't find it to be. I had issues doing installations on two different systems, and eventually left it for what I was more comfortable with. I have personally had very good luck with Slackware (10-12), CentOS (4.4 and 5) and Fedora (FC5 - F7) on a myriad of laptops. I will mention that Slackware on a laptop is not for the faint of heart! But if you're a power user or Linux pro, its great.