Paint Shop Pro by Corel is suppose to be good. I've personally experienced it before Corel bought out Jasc and it was fantastic.
I used to use GIMP two years ago before I got photoshop. Its decent at best. For freeware its pretty powerful, but doesn't come anywhere near photoshop. If you are going to be doing hardcore designing, or anything a little more complicated, photoshop is worth the money.
Still trying the x64 gmip version, not release version. GIMP + AAA-logo = a good assistant for projects, but aaa-logo(now version v3.1 or 2010) not free as we know. Just for reference only.
Another graphics handy tools from laughingbird software ie laughingbirdsoftware {.} com Do save much time on the projects ,and you can afford to get them if you like. Just my cents for reference.