Ubuntu is currently, imho, the most stable release of linux atm.
It is a ridicously compact OS and fits on a regular CD or a USB memory stick (which can be used to install from btw). It comes pre-installed with pretty much everything you need, gimp, open office etc.
I currently am running ubuntu on my laptop, which is old, and it boots in half the time that xp does, it looks better, feels better and, most importantly, runs better.
I'm not sure how it runs games and such but my guess is that pretty much anything is doable, it is after all - open source.
I don't know what else to say that I strongly recommend it for both newbies (like me) and hardcore programmers

There's a little something for everyone.
Hope this helped!
Zarx