Not everyone likes this answer, but I became one of the guys. You have to realize that you can't get ahead on your own. Your boss has to think you're O.K., your peers need to think you're O.K., and the men who work for you have to want you to move ahead. In general, the Valley is very supportive of people with great ideas who are willing to move forward. Women can do well, but it's a happenstance rather than by design.
Immigrants are very supportive of each other in the Valley.
The statistics would indicate that. We seem to have a growing gap between various groups. There's reason for concern, so there should be initiatives to support minorities. The Internet is the ultimate leveler of the playing field because it allows new companies to get access to markets with few traditional barriers. It's not the magic bullet.