Your parts look good. I too use VMware and am putting together a new system. By putting together i mean specing out parts. I don't have any good reasons to upgrade any of the parts you have on the list. The only thing i would suggest is more RAM. Since windows Vista requires at least 2GB of RAM i am going to put 8GBs in my system, 4 for Vista Ultimate 64 and the rest is so that i can run 3 other VMs at the same time. I give my XP VM at least 1GB of RAM, but with the new machine i'll be able to give it more. As far as the CPU goes, here is the one i am looking at...not much more money and i think it would be worth it.
Also, on a side note. I have found that running my VMs on an external HDD such as my WD Passport seems to make my current pc a little happier. Also, i can unplug the passport and take it with me to use on my laptop on the road or anything else. You can even keep a copy of VMware player on the external hdd so that if you are using a system that does not have VMware installed, you can still use your VMs.
Here is the RAM that i am looking at:
I hope this was helpful.