Counter Strike Source and Bootcamp

Well I tried this in the past and failed, yet yesterday I saw youtube videos of people running CS:S via Crossover or Bootcamp. I decided to give it another go and installed it yesterday and all. The problem I ran into was, it gets to the main screen and then just turns black. Im not sure whats going on, I saw some other people running it fine, is there some certain setting I need to do?
Also, I was told Crossover would work too, so I'll be trying it on Crossover later on, but for now, I'd really like to get it to work on my Windows XP side..

Have you checked the graphics settings? Perhaps they're set too high for your computer to handle.

Did you install the driver disc after installing Windows? Also, what Mac do you have?

Actually I figured it out, what I had to do was change the Launch setting to "-dxlevel 70", I had tired 80, but that was the cause of the black screen. So actually the game runs rather smoothly, however CS_Assualt, the one I liked most was the one that had the FPS lag, however I found a Cs_Assualt_Old which was practically the same thing but a bit different that ran quite well.

How do i change the launch settings?