If you go Intel, make sure you check ark.intel.com and at least verify the model supports VT-x; I would prefer one that supports VT-x and VT-D.
Are you just going to be running one VM? Also, will the PC be used for anything else processor intensive, if so, mostly single threaded or mostly multi threaded programs? If you were running the database natively on a machine rather than through a VM, what type of machine specs would you expect it to require?
We can give much better responses once we have answers to those questions. In general, though, AMD is definitely not a bad choice if virtualization is a primary task. My Phenom 2 X6 with 16GB of ram handles plenty of VM's without issue, and any AMD chip from the last several years should support AMD-V. If you have a microcenter nearby you can get an AMD Phenom II X6 1045T with free motherboard for $100, and I can't imagine you could beat that with anything else for anywhere near $100 for virtualization. If you don't have a microcenter, I would still look at AMD as a lot of Intel processors don't support VT-D, and virtualization is one place where AMD usually provides a much better price / performance ratio.(i3 2100 may beat a lot(all?) AMD processors in single threaded game benchmarks, but picking an i3 2100 which doesn't even support VT-D over Phenom x6 for something highly threaded such as video encoding or running a lot of VM's would not be a wise choice. And they're about the same price, except the motherboard for the AMD processor will be cheaper.) Phenom X6 should provide ROUGHLY similar performance to an i5 2500 or Ivy Bridge equivalent(not 2500k, as that doesn't support VT-d) for Virtualization, better than the i5 in some cases, possibly worse in others, but for a much cheaper price.