XenApp and XenDesktop are some serious maintenance, though. The installation alone (At least with version 6 that I had at my last job) was enough to make you go mad.
I use the standard VMWare Workstation. Apparently, 9 has just been released. Still looking for a way to acquire a license for that.
Running it on a RedHat box w/ 16GB RAM and an AMD Phenom II X4 processor. Hoping to up to 32GB and an AMD Phenom II X6 processor. Got a domain controller, Exchange server, and DNS running windows. IIS, another DNS server, and FTP on Linux. Running an FTP on Mac OS X Lion, as well. All of these are bridged to an ethernet adapter that is connected to my Cisco Router.