I did not set up partitions beforehand. Did it all with the Ubuntu CD during the install process. Ubuntu knew to build a swap partition so I didn't have to mess with that. I had good directions that had worked for lots of people right next to me.
Also, if you have a known-good Linux CD, run it live first (by that I mean the OS will run from the CD without making any changes to your hard drive) and see if everything appears to work OK. It'll be slow, but you can try going online, etc. and see what happens.