character animations?

Hello all,
Im trying to get some character animations going. Ive got alot of them, walk, run, and alot of attack animations(swing_sword_high_left, thrust_sword_mid, etc.). When i try to additive blend a walk and any attack i get some funkyness with the feet. Ive read abit about people seperating the character into 2 skeletons (upper body lower body) to solve this issue. Im not sure how exactly to do 2 skeletons. Any help or advice would be welcome.
-Thanks
BTW: im using 3ds max '09

Can you explain what kind of funkiness you get with the feet? Does it look as though two different animation motions are “fighting” with each other or anything like that?

Yes the anims look like they are fighting each other. Looks like the knee joint bends the wrong way sending the foot up behind the other knee and such.