What are people's opinions on the VM solution du jour?

I've played around with VMware server at home since it became free and I've always been pretty happy with it. I've now got a project to do at work which is going to require building a test system running a couple of instances of XP and a couple Ubuntu JEOS's, so I downloaded a copy of v2.0. Now I've never really liked the web management interface simply because it always seemed so damn flakey, but now v2 uses that exclusively, it's so retarded and it's made me doubt my decision. I'd like to give ESXi a try now it's free too, but sadly I don't have a whole machine going spare just to try it on, nor do I have an iSCSI target for the disc space (I don't think you can actually use the on-board storage).

While googling for some answers to a few VMware problems I've noticed a lot of people extolling the virtues of Virtual Box. I've downloaded a copy for OSX and am currently trying an install of xubuntu on it. Pretty good so far, it seems much quicker than the instance that runs in my copy of Parallels.

What are you guys using? Should I stick with VMware server 2 and sweat out the frustration? Should I go back to version 1? Should I give Virtual Box a proper try?