Virtualization Planning 
Turns out that Parallels releases a version of their software for Linux (ref:
downloads page). The documentation claims this to be a Hypervisor instead of just a virtualizer (ie the original VMWare solution, although the top-of-the-line solution is now a hypervisor as well).
- Parallels Workstation, US$50.
- Parallels Compressor Server, US$180.
- Parallels Compressor Workstation, US$50.
This product will run Windows XP/Pro, although DVD/RW drives are seen only as DVD drives.
Also in the news, VMWare 1.0 is free; although this is a non-hypervisor virtualization product.
So I think we will do this:
- Run CentOS 4.3 64-bit
- install Sun Ray software
- install VMWare 1.0
- install XP into a VMWare virtual server
This should let me do pretty much everything I need to do at the moment. We can also wait for Xen to mature.
At some point it may be worth while getting a free trial key of the Parallels system and doing some comparisons to see if there is anything to be gained for US$50, a trivial amount of money to spend especially considering Parallels will support the virtualization functionality of my Pentium-D processor.