Adobe Photoshop is a fabulous program...but for most people who just want to crop. maybe edit red-eye out, and resize it is big-time overkill. Besides the price-tag ($600), it's very confusing if you don't want to do what graphic designers/artists/professionals do. That said, I do use it for work and for my web design and graphic design business.
It will do anything you can think of doing, but it is complex and expensive.
Photoshop Elements is a very good alternative. It is priced at or below $100, and considering what it is the price is very reasonable. It loses many of the bells and whistles that the average user won't ever miss to begin with, but pretty much all the cool stuff is still there.
For very basic photo editing, like cropping and resizing, Irfanview is free and does the trick.