Hi there
If you don't actually need 3-D video support on your Virtual machines then the latest version of VMWARE SERVER 2.0.2 could be for you.
It's free and BIG advantages of running Virtual machines with SERVER software are :
1) The VM's can be started (and stopped) in the background so a User doesn't need to be logged on to the host to activate a VM. VM's can be started as a SERVICE so these are automatically started when the HOST system is booted -- without needing any user to logon and activate them.
2) A USER can LOGON to a VM without having to have an account on the HOST machine.
3) If the VM itself is a Server then the user can logon to an application DIRECTLY on the VM without having to have a logon session to the vm itself.
4) if the VM is a server then you can post a link on the desktop from your HOST machine to the application on the vm itself - this means for example clicking on the application on the HOST machine will take you straight to the application running on the VM - this is great for loggging into say ERP software such as SAP or other DB based applications.
How to install VMWare server in windows vista | ZeroHacks
(The article says VISTA but it works fine with Windows 7 both 32 and 64 bit versions of Windows).
Note you CAN also provided the VT feature is enabled in your BIOS run 64 BIT GUESTS even on 32 BIT HOSTS with vmware server (and workstation of course). In this case the Host will only see 4GB RAM (max) so your VM's need to be configured accordingly.
This software also works on Windows Home Premium BTW and the resulting VM's work pretty fast too.
Cheers
jimbo.