Well i got virtualisation working with Virtualbox, although it is not completely stable. It is fine as long as i do not change any of Virtualbox's settings. The other glitch is that when I try to resume virtual machines' saved state, it just errors and I have to discard the saved state. I've been trying out Slackware 12.1 which finally uses the 2.6 kernel and uses HAL and modular X.org by default. My other virtual machines are Kubuntu 8.0.4, KDE4.0 version, for testing the latest nightly builds of Amarok 2 and also Windows XP, for testing and for when I need a specific Windows only program.
Also, I am annoyed with Ubuntu 8.0.4 for having a bug in Nautilus - it won't mount USB storage at the moment, there's bit of a buzz on forums about it. My workaround is to point Konqueror at media:/ and mount and unmount it there, which works fine. Obviously it 's fine for people who have KDE libraries installed but not for those who like a simple Ubuntu install.
Update: Ubuntu has frozen up completely today, twice. Both of these involving USB. I connected my kodak digital camera earlier and it froze, then just now it froze scanning for a printer, I am really getting annoyed with it now!
Update 2: I have found the common denominator for both crashes - Amarok, my favourite player was running both times, and searching for a printer works whilst Amarok is closed as does connecting my camera.
Update 3: I have solved the above problem, by disabling PulseAudio completely by selecting alsa for all options in /system/preferences/sound. It's a shame, as I quite like some of it's features, like network audio and individual volume controls for programs, hopefully it'll be improved in updates. Like Firefox 3 beta, it should not appear in an LTS release.