Hi, I don't really know where to post this, as there are no software or OS forums...

I am buliding a new rig: e8400 | 4GB DDR2-800 | 7900 GS, and will be
using my old computer as a separate rig. However, I will still need to
buy a new OS for the other rig.... what I'm saying is I will be able to
get Vista Premium for only $20 more then just getting another copy of
plain old WinXP. I would put my old WinXP Home copy on the old rig, and
Vista on my new rig... that is if it would be worth it. Back when Vista
came out I read a lot of crap about how Vista sucked compared to XP in
performance benchmarks. Now with SP1 out and more updates, does Vista
perform better then it did before? Would it be worth it to get Vista
now.. when I can save mass cash? If I were to get Vista would I get
Vista 64 or 32? Thanks.

In a word, NO! At least for Vista x64 SP1 was a complete disaster, creates more problems than it solves and still is 10-50% slower in some DX9 titles.

Not sure about Vista x86 (32bit).

Get Vista if there is a DX10 game you MUST have and MUST play under DX10 API. I have ALL the DX10 game titles for Vista and not a single one really looks significantly better than the DX9c version. UAC in Vista is horrible BTW, turn it off immediately if you get Vista. Vista is VERY buggy with older (as in 1-2 years old) DX9 titles.

Again this is all with Vista x64, don't have any experience with Vista x86.

My hope is Microsoft actually start to listen to what consumers want -- most likely a fantasy. But the sooner Vista is replaced by something else (anything else), the better for all.

SP1 is definitely NOT the what I was hoping it would be.

if you are bulding a new rig than install vista it will take advantage of all your 4 gb of memory and in the future when you upgrade to a dx10 card you will have a dx10 you wont need to install new os

Actually Vista 64 bit will take advantage of 4 gigs, 32 bit wont, why not dual boot? You do know you can have xp running on 3 personal home computers without breaking any contracts right? Also vista sp1 is yet to be seen, people had issues with a incremental update, and ms pulled it until next month, and then you can d/l sp1.