I did a fresh installation (with the AMD64 version) as I had just upgraded my old Intel Pentium 4 to an AMD 64 X2. Because my /home lies on a partition separate from the root partition, it was left intact, and not having to reconfigure all the applications saved me lots of time. :-)
Ubuntu 9.10 Karmic Koala is still in Alpha at this moment, so you're advised to install it only on a test computer.
"You are using Ubuntu 9.10 - the Karmic Koala - released in October 2009 and supported until April 2011."
I must have time-travelled to the future. :P
Upgraded to Ubuntu 9.04 (Jaunty Jackalope)
Upgraded To Ubuntu 8.10 (Intrepid Ibex)
Hardy Heron is nice
Upgraded To Ubuntu 8.04 (Hardy Heron ) LTS
Noob Screws Up on His Ubuntu Gutsy Gibbon Upgrade
Upgraded To Ubuntu 7.10 (Gutsy Gibbon)
Upgraded To Ubuntu 7.04 (Feisty Fawn)