Welcome to SBB!!! So glad you found us here
Val mentioned some great programs! They are very widely used around here...I'd say the most common are the Digital Image Pro, Paint Shop Pro, and Photoshop.
But...I'd like to mention another that is not quite as widely used, but I think you'd definitely benefit by including it in your research! It's Ulead PhotoImpact 8. It's comparable in price to DIP and offers the same ease of use and versatility (if not better!).
I wish you much luck in your search for a better program that suites you best, and I can't wait to see you get started! It's soooo addicting!
:P