I just saw this today from innotek and have downloaded the binary version and installed the product this evening:

http://www.virtualbox.org/wiki/Downloads

I've installed a guest winxp in VirtualBox on LE2005 and it seems to be working pretty good. Haven't had a chance to thoroughly test it and there do seem to be a few bumps in the road but it's running winxp pretty fast; right now I'm doing updates. It is ram hungry like most virtualization software and no 3d/games AFAIK.

Thought I'd pass it along if others would like to try.

Here the other way round, running Mandriva 2007 as guest, inside Win XP with VirtualBox ...
(actually first running MCNLive Cherbourg as .iso/cd, then installing it from the running iso, and running it from the virtual HD), pretty fast on my box:

http://www.mandrivaclub.nl/site/index.php?showtopic=7815

(warning: with screenshots)

--chris