For a bit more immersion have a look at the SHIV Speech thread. Instead of pressing Q you can say "Open tube 1" into your mike and it does the same thing.
I was using it on my old system and it was a hoot. I've got a new system now with Windows 7 but haven't gotten around to installing SHIV Speech.
IMHO it's worth a look. It isn't perfect but if you read the thread you can get a feel for whether it's worth it or not. Installing it is fairly straightforward but involves 'teaching' Windows to recognize your voice etc. I will say it is pretty damn cool to say "Come left 10 degrees" and have the 'crew' react or "Up scope" and the Attack scope goes up or "Crash dive!" and down she goes etc. The downside is that anyone else in your house will think you have lost it, LOL.
