We have Dragon Dictate for the Mac. Our ds12 prefers this over typing, but I don't think it would have worked for him at 6.
FWIW, ds has also played around with Dragon on our iPhone (it's a free app) and the voice recognition seems to be much easier to use there (no training required for the software to understand your voice). We've been told that the reason is that the Dragon iPhone app is operating off of an online voice recognition database that's trained to 1000s of voices so it can catch most words easily, as opposed to having to train to recognize your individual voice as you have to do on the computer version. The phone version isn't a complete substitute for an older student's needs, but for a 6 year old it will most likely work great! You can have him talk into the phone, then email what he's said to wherever and cut and paste it into a text doc. You can probably save it as text to - I haven't used it lately and I'm not at home where I have my AT notes
Another thing you can do if you have a Mac (for a young child) is to record in Garage Band and just leave it as a voice track.
Gotta run, hope that helps some!
polarbear
ps - Pemberley, I don't think that the Premium version is significantly different re operating with background noise. I do think the headset used might make a difference? We were also told (fwiw, it's been a few years since we were looking at all this the first time) that there was no need to purchase the premium edition for a student.