Go here for GIMP
GIMP - Downloads

Its an Open Source program, which in basic terms means that the source code is open to be modified by anyone rather than proprietary like Widows. It is a GNU/GPL license which just basically means it is free to download and use. You dont need Limewire or anything like that to get it.

Here is another great graphics program
www.paint.net

It doesnt have the capabilities of GIMP but its a bit easier to use and also free

I have Photoshop CS3, GIMP and Paint.Net. I use GIMP mainly but when I just need to make minor adjustments to a photo then I'll use Paint.NET. It loads a bit faster and is easier to use, but if I need to do anything complicated, particularly with layers I'll use GIMP.

Ive also used the Logo Design Studio as Im not much on doing artistic things like making a logo from scratch with GIMP or Photoshop.