Hi Dusty,
VAST runs fine on Win x64, but it is a 32 bit VM. You need to keep that in mind when you connect to DLLs or ODBC data sources.
At least for Windows, there is no 64 bit VM (yet?).
I don't know about Solaris or AIX, but the same is true for Linux (so never forget to install ia-32 libraries on your distro).
Joachim