I have Ubuntu-64 on my desktop (Used it for a long time) and have no problem with it except of flash player bugs (I'm not sure that it's because of 64 platform but I heard that exactly because of it).
Also I had Ubuntu on laptop, but recently I've installed Linux Mint (Debian based), just for try - Mint is also great!

to Hanna:
How with the legality in Sweden? Does people uses a licensed windows or prefers pirated? How about other proprietary software?