I just tried it, and I'm downgrading to ubuntu 32 bits for the following reasons:
- I cannot run multiple instance because apparently this require VT-x technology to be enabled, and by doing so, only one guest can run at a time
- I had woes during the installation, then after again during apt-get upgrade I noticed segfaults here and there... I don't trust it too much
That being said I don't know what part is to blame? VB 2.1? ubuntu 8.10? Intel plate-form? or the host: leopard.
not everything is good on the 32bits version. I filled a ticket about a bug in vboxsf (shared folders)