I'm assuming you're installing Vista x64, not XP x64.
IMHO, here's some tips that although they apply to both 32 and 64-bit, my conscience forces me to give my 2 cents:
1. Use
vLite. Among other things, I use it to force allowing me to use the one, true (normally hidden) Administrator account. Besides bypassing UAC (or maybe because of it) several things that work in a way I don't like in normal Vista installations work more closely like they did in XP. I never made up a list and never ever install Vista the normal way anymore, so I don't recall what all they were exactly, but I know "Open With" behaved differently with some programs. This is true of Vista SP1 as well as I did try a plain jane SP1 install just to check it out.
2. There's much debate about RAID 0 stripe size and file system cluster size, and it arguably makes little difference, but here's what I believe in:
I use a 2-disk RAID 0 with a stripe size of 32k and a file system cluster size of 64k. I once calculated the average size of the files in a Vista installation compared to XP and it was indeed higher. More than that, I deal a lot with video and other large files so the large cluster size doesn't result in much, if any, space loss. The cluster size of 64k and being double that of the stripe size results in half of each cluster being stored on each hard drive of a 2-disk array.
If you're dealing with large files (games generally do, too), then the result is optimal as it's more efficient to deal with large files if the cluster size is large, plus both hard disks of the array are more or less equally read and written for storing the large files.
3. I still use a pagefile manually set to twice the minimum and maximum that Microsoft recommends. I also put the pagefile on a different partition or even on a different (as long as it's equally performing) hard disk.
The size for you with four gigs would be minimum of 12 gigs and maximum of 24 gigs. Wow. Yes I know that's huge. This also reduces the chance of pagefile fragmentation since it's not "system managed" and therefore up to the o/s to resize it as it likes. It's also a lot less likely to resize since it's twice MS's recommended values.