I found a good Black Mesa wrapper on Porting Team, installed Steam for windows in the wrapper, and then installed Black Mesa. Steam opens when I open the wrapper and then I just choose Black Mesa from the games list. Runs like a dream. The only problems I’ve seen are with the flashlight. Having it on gives you a choppy framerate (although I am running the game at 1920x1200 with 4g of RAM, so your situation might be better) and sometimes, instead of shining white light, it projects colory cubemap-ish textures or partial screenshots of my desktop and doesn’t illuminate what it’s supposed to, like what’s right in front of you. Go figure. I leave it off unless I’m in a dark room.
AND you’ll have a 12 gig file size application.
Macs prevail.
Can’t wait for Xen.