So, I finally made the switch to Ubuntu. I'm afraid Windows Vista was the final nail in the coffin for me. I had to buy a new laptop with 2GB of RAM just so I could run it at an acceptable speed, it didn't even come with MS Office (so I was using Open Office anyway) and it just seemed horribly complicated.
Ubuntu, by contrast, seems to be fairly easy to use and it 'just works', which is nice!