Best OS for VMware on a laptop

[ZuG]

Hello.
I want to run 4 instances of Windows XP on a laptop. Would running 2008 Server be the best option as a base OS with windows XP vm's on top of it?

Can anybody explain how access to the USB ports is handled when there is a base OS. If I have a USB device, would I need drivers for the device in the base OS so the Windows XP VM can see it?
Cheers.

 

[ZuG]

We installed VM Workstation on a Windows 7 64 bit laptop and it works well. However, we can only install 2 before the performance is affected. The USB devices are 3g dongles and interesting we found there was a large performance hit on them as the CPU load went up.
We are getting a better laptop