Is Parallels on Mac Pro 64 bit or 32 bit?

Basically, does the OS running inside Parallels see the hardware as 32-bit or 64-bit?

For example, should I download the 32 bit or 64 bit version of Ubuntu Linux to run under Parallels on my Mac Pro....Or install the 64 bit version of Windows vs the regular 32-bit version?

Thanks!

 

One of the Parallels people came on here to tell us that it would only support a 32-bit environment.

 

I just tried installing Fedora Core 5 x86_64. It wouldn't load, and suggested I use the 32-bit version instead.

Mike