The better the microphone the better voice activation will be, mostly the blocking out the game noise and keyboard stuff. This is mostly why vent's settings have mileage will vary written all over them.

Its not clear if you have tried using the vent voice activation or not from your post, its pretty easy. Especially if you can login twice to vent and test it out on another computer playing the sound back to yourself to make sure you are understandable, bang on the keyboard a bit and so forth, without doing the embarrassing 'can you hear me now' stuff over and over.

Btw, if you have a cellphone handsfree set, you might give that a try if your computer has blue tooth. That's what I use and it works great. I use the motorola sd10-hd.