Can someone break down LiPos for me?
I get the #S is the number of cells, but what does the mah and ##C mean?

What is a good pack to use in racing a 2wd or 4wd SC truck?

There is a lot to explain with Lipos and I tend to get off topic so here you go:

http://www.rcgroups.com/forums/showthread.php?t=209187

http://youtu.be/yJ-QyHiiqUI

Hope these help!

And here is a decent guide on how to take care of your batteries:

http://www.fantomracing.com/lipo-instructions.php

Good stuff...thank you for the links!

Here's another...http://www.rchelicopterfun.com/rc-lipo-batteries.html