I played it on the 360. Absolutely horrible way to control it.I never played it on Windows 7, but just as a heads up the game is kind of rare. I got it a loong time ago at Circuit City for like $3 on clearance and was surprised to see it going for $25-30 on Ebay recently. You may end up shelling out more than you were anticipating for a game this old.
If you have a 360 that one might be a little cheaper.
I have it working on Windows 7 too. It worked right off the bat. Go to eagames.com and buy Rise of the Witch King. EA lost the license for Middle Earth games so BFME2 is really hard to find. The expansion will play without the original from eagames.com and they dont need a license (no Middle Earth in it or something).
Just get Medevil: Total War II and install the Third Age: Total War patch. Much better, though perhaps a bit too advanced for a 12 year old?