-get vista 64 home premium. 32 bit OS's can only support 3 gigs of ram and vista basic from what I've heard can only support 1 gig of ram
-get a higher PSU 750 watt (has easier time handling SLI configuration if you upgrade later)
http://www.scan.co.uk/Product.aspx?WebProductId=501972
this case is 5$ cheaper (antec 900)
tell me if this was helpful at all