Best code reader/scanner?

[killthewabbit]

On my drive in to work this morning, my Service Engine Soon light came on. Since I plan on keeping my Tahoe for awhile, I'm planning to dig into it myself. I'm not really a stranger to a wrench, but I've never really done anything too extensive on OBDII vehicles.

I'm assuming I'll need a OBDII code reader/scanner to diagnose. I have a couple questions:

1. What's a suggestion on a good but reasonably priced code reader/scanner? I have no Matco/Snap-On trucks circling my office park, so I'd rather keep the list narrowed down to something easy to get my hands on
2. What resources do you guys use to decipher and troubleshoot codes I should be reading from the above scanner?

Thanks in advance for the help