So I must admit that even though speech recognition in Vista was created by one of our partner groups and I know several people that worked on it, I didn't actually try it until this weekend. Although I never installed any of the betas, I did pick up a copy of Vista Ultimate the day it was released and installed the 64 bit version on my machine at home. The machine was built explicitly for Vista and has an 8800 GTS video card and 4 GB RAM. Still, I have had a number of problems with Vista and the fact that I couldn't get my microphone to work kept me from trying out speech recognition.
Finally, after seeing that Asus had come out with a new version of the 64 bit drivers I tried again and it worked. I went through the speech tutorial and I have quickly found it very useful. In general it recognizes my voice for standard commands and does a decent job dictating. The only problem is the fact that we have a very noisy house - my kids have two volumes - loud and louder. I usually keep it in sleep mode but occasionally it wakes up and tries to understand what others are saying.
My next step is to integrate the new SpeechFX API into the new version of my vocabulary program. I will post more details of my progress as it occurs.