Personally I would be buying a 8800GT 512mb, the almost as good as the Ultra and about 1/2 the price. Best bang for buck. The difference in RAM amounts between 768mb Ultra and 512mb GT will be minimal.
Personally again I wouldn't buy a MSI card, I prefer Albatron, Gigabyte or Asus.
Put the extra cash into more cpu power.
Get XP over Vista, I have used Vista for 6 months now and wish I could install XP on my laptop, unfortunatly I struggleing to find all the drivers I need