ive just installed vista aswell as XP on a dual boot setup and IMO
stay with XP unless you have much patience and a very good PC with teh following specs i had such poor performance from vista
1GB 400Mhz RAM (oc'd to 440Mhz)
ATI RADEON X1950Pro 256MB graphics card
2 IDE HDD's
NFORCE3 mother board
AMD 64 VENICE 3800+ @2.4Ghz
all in all thats a pretty decent setup and will pass XP min requirements many times over but vista, is my mightmare drivers for my new GFX card screwed it up even though they are for VISTA, and i had around 100MB spare when vista was idle (no windwos or apps running)