Thats fair enough then, in that case your options / work arounds are:
Firstly i would think there would be a way to get the soundcard working on a 64 bit OS, surly it can be done
Other then that...........
Stick with 32 bit windows and live with 3.5 ish GB
Move to a 64bit OS - Which would then lead onto accepting that your guna have driver problems, and do without things working, or buy new bits which you can get 64 bit drivers for.
Dual boot a 32bit and 64bit (whether it be Vista or XP, or one of each), having one set up everyday use (32 bit), with everything working, and 3.5gb still being enough 99% of the time, and then have a 64 bit set up for when your working on some editing or something. This would be really easy to set up, and effective for what you need, and would be pretty slick IMO.
The other option, and its not something i have really played around with, would be to install a 64bit OS, and then run a 32bit virtual machine, using VMware workstation or similar to get everything working, your pc would easily run a vitual machine, and then you can kill it when you wana get on with some editing.
I think personally i would dual boot it, 32bit for everyday use, and 64 bit for hardcore use.