Sticking with the 32bit version isn't a horrible idea either (if you don't mind it). I did the 64bit on my dad's AMD I recently built him and there were a few gotchas due to the lack of full 64 bit support in some software packages (like flash, his print driver, and a couple others). I was pretty close to dropping the 64 bit but ended up finding scripts to get stuff worked out. He likes it a lot but still has questions from time to time. Once I get him off his piano tuning software (which requires Windows due to a stupid USB dongle) life should be easier. VMWare still has some issues from time to time for him.
The thing I like about Ubuntu is the 6 month releases; with each one, I keep having fewer things to complain about or that require some obscure shell script to fix.