Re: WinXP Pro 32 or Vista64 ...?
Yeah, the difference will definitely be noticeable with 2 more Gb in there. But if it makes you feel any better I had no trouble with it after SP2.
I also installed it on my brother's rig (same specs) and he's having no issues with it either.
I did spend a good deal of time searching out tweaks and such though - I'm sure you've already looked into that.