Hiya,
I used to have rats they're really lovely pets. I would advise to get 2 females (the boys have HUGE b*ll*cks and tend to pee on you) and get a good cage which had solid (ie plastic) platforms rather than mesh/wire. (I had a rat that got its legs stuck through the wire and fell - he ended up breaking his leg and had to be put to sleep

)
Try to feed them a good diet too. They LOVE junk food but keeps the treats small rather than making up a large portion of their diet with them. It seems to affect their health when they have a crap diet. Just like us really!
I just brought mine from a local pet shop. I wanted to do this rather than buy a 'fancy' breed as I knew lots of the rats from the pet shop would be brought by snake owners.
They're really easy to tame and have lovely natures, and really clever too
http://www.youtube.com/watch?v=5lHx7dp230w
You're making me want to go and buy some now lol! x x x