If you have problems getting Ubuntu Hardy Heron to work properly, I strongly recommend you check out Intrepid Ibex, the newest release. I'm having way fewer issues with it on my Toshiba Satellite notebook (if you are fine on Hardy Heron perhaps "upgrading" will mess you up). The UI also seems slicker. Not nearly as smooth as OS X, or even Vista, but a definite improvement. The Wubi Windows Installer makes it really easy to take it for a test drive without compromising your access to your standard OS, you don't have to go "all-in."
It went on to my newly acquired five year old HP laptop like butter on hot toast.
While I'm still waiting for my new Mac to arrive, I dare not fiddle around with my only computer at home, so I'll wait a bit with the upgrade, but it is certainly on my TODO list as soon as I have a back-up computer if everything goes south :)
A warning: tha latest update of Ibex on my Acer Aspire One killed all networking. There is some tricky bug in the new kernel image. Booting the older image in GRUB enables wired ethernet, but I'm still waiting for a cure for the WLAN part...
The new ubuntu release has problems with running under vmware fusion on a mac: I "upgraded" and had to go back to 8.04.
Henry