So I upgraded to Ubuntu 10.04 some time back. I did the network upgrade from 9.10 to 10.04. Without a doubt, the easiest online upgrade I have ever done. The weird thing is, I vastly prefer to do a clean install, but I could not get the 10.04 CD to work so I crossed my fingers and went for it. Only thing that did happen was Ethernet didn't work (and I had to scramble to remember the ifconfig commands). I traced this back to the way I had configured /etc/network/interfaces.
Couple of things I did do:
Un installed the Nvidia video card drivers and switched back to the stock vga driver.
Backed up my home directory.
But really, this even went better than the 9.04 to 9.10. I had to reach in and tweak the GRUB settings from a rescue CD after that upgrade to even get GRUB to boot.