I flogged it out a few months back but lack of drivers was a problem for me for the Matrox Parhelia . Went back to XP Pro . Vegas works in the 64 XP OK. Will probably switch when Vista comes out.
Vegas and SoundForge work perfect for me in x64. But Acid does not.
By the way, of all the software I own, which is a lot, Acid and a Toshiba MP3 player device DRM music copy application are the only applications I found that do not work with x64 Windows.