If you are running Steinberg or Midex music software or hardware (MIDI interfaces for example) check compatibilty because some "older" products are not having drivers issued.

If you are aiming to run 64 bit processes you need Vista, likewise if you run stupid amounts of RAM (VISTA will address 4Gb) the same applies. Son and heir to family overdraft built his machine to run VISTA and in 2 months it hasn't crashed. However because of the first issue above he has set up a XP partition for some of his music applications.

All the best

Steve Ogden