OFP is a fantastic game, with tons of mods, and still tons of online action, (check out my gaming groups site,
http://www.tacticalgamer.com, we have two open servers up and they have players almost nightly.
For 9 bucks you can't beat that price...get it, get SP and MP action.
BUT... a re-make of OFP is due out this X-mas called Allied assualt... so you might want to wait.