Can anyone tell me if there is a cost to playing this game online on pc other than buying the actual game? If I get the boxed game or get it on steam is there a online cost or is online free?

If it requires a monthly cost it will say so on the package, or it will be written with ugly fat text all over your screen on steam and similar download services.

No, you can buy it and then play untill you die for free

so even the multiplayer is free? b/c one of my friends said you had to pay for an account on the network kinda like an x-box live.

Multiplayer is 100% free as long as you have an active Xbox Live Gold membership. The PC requires nothing but an internet connection.