PC Configuration recommendations for multiple VMware machines

i would steer away from x64 edditions for multiple purpose use computers  as there are still a ton of driver related issues with it.   Mass storage space and memory are your biggest concerns for the vm wares. depending on how much memory you want to allocate to your virtual machines. to give you an example of a vmware running configurations about 2 years ago i build a box for testing and demonstration purposes.  with a 3ghz intel processor (non dual core)  2gig of ram  500gig of storage.
i would allocate between 256 and 512 to the individual machines (which ranged the whole gambit win95-server 2003-linux) and would be able to have 3-5 virtual machines running conncurently with vmware workstation 5.5 relatively stable   each vmware machine was allocated 10- 50 gig (using the dynamic growth method) and was over all more than pleased with it.   the use of the computer as a gaming machine and vista machine really have no bearing on its spec's as a vmware running powerhouse just about everything good for gaming will increase its usability for vmware and vmware has a vista version available so should be no additional concerns there except for the fact that vista uses conciderably more memory for the host os leaving less available for guest os's.

hope this helps

Thank you very much for your comments. To give more details, the VMware machines that I want to use requires lots of memory, and I want to use about (or more than) 4GB RAM since the prices are reasonable these days but my limit is XP. Maybe my question should be how I could override the 3 GB RAM limit on XP OS. Any ideas about that?