Take the plunge and either pony up for a copy of Photoshop, or save some bucks and get a copy of Photoshop Elements (can be found for VERY cheap).
The more editing you do, the more you'll realize that Photoshop is the inevitable end of the road in terms of quality and tools.
If you do strictly photography editing, you might actually be pretty happy with Aperture (or Adobe Lightbox, which is still free in Beta for a while). The editing tools in those are pretty reliable.