How big is the online community for older games on Xbox 360?

I’m getting a 360 for Christmas, and Gamestop is having a buy 2, get 1 free sale on used games. I figured I would stock up on somre older games for cheap while the sale is going on. Do people still play online for older games or has everyone jumped to the newer stuff. For example, would I be able to play Bad Company or the original Modern Warfare online?

The online community for console games tends to only last until the next big game comes out unfortunately. Except for the HUGE names (Halo, Modern Warfare) they become ghost towns within weeks of the “next big thing” in whatever genre you play in.

That’s one thing it always seemed PCs were able to do is keep people playing previous versions of games longer.