Going for that amount of RAM warrants looking for a descent mainboard first. One that supports this memory, and some extra if you might later need it. These boards support VMX in all cases, and the high-end CPU's supported also do.
Maybe you should go for a server mainboard, it can be had with multiple CPU sockets, so if a quad-core isn't enough for running all your VM's, you can add a couple more. Hm, then go straight for a XEON system, of the latest X56xx series, it really has superior VM performance, and is available on systems with lots of memory. But I'm not sure anything but Server OS's (Windows Server, VMWare ESX, Linux's) can boot from that board and what storage should be connected.
Oefff, I got a little excited

, but it was fun
