The 2623D7U looks pretty good, but IBM says 3-6 weeks delivery. $1800 at IBM.com
If you want to configure a T60 yourself, they offer a 7200 rpm 100 GB hard drive for $220 - $120 more than the 5400 rpm version.
I assume VMWare on Ubuntu will work with both processors in the Duo, but didn't see anything specific about that in a quick browse at vmware.com If they don't at present, it's hard to imagine that they won't soon. Ubuntu should have no problem with it (Linux has done SMP for a long time).
In situations like this, I usually decide what I'm willing to spend and then get the best machine I can for the money. It rarely makes sense to buy top-of-the-line.
Luck!
Cheers,
Scott.