Lightroom (LR) (Windows) & Aperture (Mac) are good for light editing etc. They shine in other parts. LR has Library, Develop, Slideshow, Print & Website (keywording grouping etc etc.). I'm not familiar with Aperture despite also owning a Mac. LR can be installed on both platforms.
As TB mentioned Elements will most likely do more than you'll ever need. Photoshop CSxxxx is targetted at professionals and has a steep learning curve, and is pricey.
I'd suggest you go for Elements if you want to do reasonable editing, and you can take it quite far. If then it turns out you've outgrown it switch to Photoshop.