Probably worth talking about the vmware setup here, too.
First off, I'm using VMWare Player. I snagged images for Debian 5.0, Ubuntu 9.whateverthehellthey'reonnow, and Fedora 10 from ThoughtPolice. Gave each one of them static private IPs, and setup their net interfaces to use a bridge instead of NAT so I could have full network access to them directly from the Debian "ohmygodit'sstillrunningetchtesting!!!" laptop. I also setup a shared folder on the host XP machine, and have each of the images smbmounting it on boot so I can easily move files around. Currently considering setting up Active Directory on the host and mucking around with pam_ldap auth off of it, but not motivated enough to find the XP64 install cdrom at the moment. Machines are using a MySQL 5.0 server running on the XP host (and, by the way... MySQL admin on windows is an absolute pain in the butt).
The Q7760 proc seems to be handling it all in stride despite being a tad old, and 4GB mem appears to be sufficient for the Rube Goldbergesque virtual network I've created. Disk space usage has gone up, but with 1.5TB drives at $120 now, expanding that shouldn't be a problem.
Yay virtualization. :)