Yep, mirex is right, it's Mechwarrior 2. It had Clan Wolf and Clan Jade Falcon to choose from.
3 (IIRC, I haven't played it) had Inner Sphere agains Clan Smoke Jaguar. First one didn't have any clans, but was very good game, though. No idea about the fourth one, haven't played it, and I'm pretty sure that there is no 5, yet.