Hey Jacksonville! I'm in Pensacola ...
If you're serious about learning and using the software that really does what you want, I'd say there's only one choice - Photoshop. I'd start with Elements 6 (If you're a Mac user like me, wait until the end of this month. That's when the newest version, Elements 6, will be avail. for Macs)
Around $100, and you get a very sophisticated program that is plenty for most people - including a lot of professionals. It can certainly do the selective color thing you mentioned. In fact I have a tutorial on it, based on Elements 4 & 5 but easily converted to any version of PS.
Here's where you can go to check out the tutorial:
http://www.jimsdigitaldiary.com/colorizing.html
OK, yeah, there are a ton of other programs out there, some of them are free. But believe me, Photoshop defines this industry. Everything that any other program can do PS does better and more professionally ... and they probably invented it anyhow.
If you ever get serious enough to consider the professional version, yeah, it's expensive. but you'll know when it's time ... and if it's worth the extra $.