FYI,

http://store.steampowered.com/news/5596/

Activision will be hosting a Free Weekend for Call of Duty®: Black Ops for PC version only! Pre-load the game now and be ready to play when the free weekend starts on Thursday, June 2nd at 10am Pacific Time.

The Free Weekend of Call of Duty®: Black Ops will let you play the entire multiplayer portion of the base game.
For those who wan to try to play this game on PC, can download it for free and test it on ur pc and see how Black Ops is going on the PC side.