Innotek Virtualization
The hottest new alternative to VMWare/Xen/Qemu is Innotek’s VirtualBox. Free and kicks-ass- you have seamless mouse integration, a shared cliboard, easy sharing between the host and guest’s, support for USB ..and if you are still hungry you actually have complete seamless desktops across the host and guest.
The installation is not too complex- just get it and install it on your boxes- http://www.virtualbox.org/wiki/Downloads
As far as I remember all I did- for the current version was install “Guest Additions” which you will find in the Devices Menu once you have powered up a guest. It was a bit difficult getting usb cameras working- you ll have to fool around a bit.
In previous versions (<= 1.4) it was difficult starting up seamless desktops and sharing etc- seamless desktops had to be started up with an rdp connection – 1.5 is better and faster. You wont notice a glitch!
Some shots:

[The XP taskbar sits neatly over the gnome panel- although i think this still requires more improvement. It would be better to have the Windows programs docked into the gnome-bar itself. Like the Macs do virtualization]






