Install the game, run it, see how it plays. If it's too slow for you, then start a post.
But.. COD Black ops minimum system reqs are here http://www.gamestop.com/pc/games/call-of-duty-black-ops/77795#productDetails
And your P4 system is way bellow what they want. You need a faster dual core CPU, 2.5 gig + and a gaming video card to run COD Black Ops.