I'm having a similar problem.
Steam is being incredibly annoying, it takes ages to load up (keep in mind, all my other applications except for Crossover Games are not running while I'm doing this.) When it FINALLY loads up, I click on Team Fortress 2 to launch, and so it does (taking about a minute to do so). Then it brings me to the game's loading screen, and takes about a long minute to load. I've tried to bring this game into a window, but when I do, it all of a sudden only appears in the bottom left of the screen, and the rest of the screen is just black. So then I go onto the server list, and the screen starts glitching like MAD. Strange dots of colour, and dots and lines flashing across the screen, it looks INCREDIBLY dodgy. So I'll wait about a minute for the server list to stop refreshing, and I'll click on one. Now one of two things happens here: It either has a little window pop up and says something like "Server could not be found/connected" and it won't connect. Or, it brings up that window for a fraction of a second and then goes onto the "Loading server" screen. However when that window pops up for that small amount of time, it does actually say "Server could not be found/connected." Anyway, when I get onto the loading screen, another two things could happen here: It either stops loading at three bars and freezes, or it loads for a bit longer until a sign comes up saying "You are on your way to ..." I have never reached the actual battle ever, which is incredibly disappointing because I waited 2 months to buy the Orange Box, and when I finally do, I can't even play it.
However, what I don't get is that Portal (also from the Orange Box) works completely fine, with no framerate issues, the graphics are great and except for crashing every 15-30 mins and a few problems with the subtitles, you would assume every other game would be as good as that (performance-wise). I have not installed the Half-Life games yet, they take up too much memory.
I NEED ANSWERS PLEASE!
P.S A lot of people have been talking about boot camp being great and all, but doesn't that cost hundreds of dollars? Educate me please lol