hahaha... I did the same big, for my birthday I purchased it for 12$ this year... then saw it for 10$ at the next store. (last week or the week before... I forget)
I still have to install it and try itout.
As for RTCW;
It's not much like tribes at all.
Ever play woldenstein 3d? It's an oooold ass game, and this game is a sort of sequel.
You have several classes to choose from on each side (nazi or allies) and a few different weapons for each. It takes place in world war 2 europe, returning to a castle in germany which your character escaped from in the first wolfenstein 3d.
It's pretty cool I think, but I prefer single player mode.
Adios!