On Kim Komando this morning she said Vista has speech recognition built in. I haven’t played with it, so don’t know how good or bad it is. I do know Microsoft Sync in Ford vehicles works darn well, if they used the same code base for both products.
My Sony laptop has Vista Ultimate and the speech recognition is extremely good. It requires no training so you can start usig it right from the word go. I would recommend a bluetooth capable laptop with a bluetooth microphone so your voice can be picked up even if you aren’t directly facing the laptop built-in microphone.