There are other threads on this very topic on this site and you might wish to search for those.

I use the preferred version 9.0/9.5 (9.0 is for XP, 9.5 for vista)and have been impressed with its medical vocabulary. Ver 10 will only work in an EMR with the Medical version. I don't see the value in the medical version yet another user likes the templating options. (I did buy ver 10 when it first came out yet have not installed it yet so I can't comment on how much better it may be. Dave Pogue of the New York Times thought it was about 10% better). Many of my colleagues have the Medical version, yet they aren't always paying for it themselves (they are employees). If you buy ver 9.5 find it from a reseller/liquidator and avoid ebay as the versions on ebay are often not legitimate. Be aware the box may say version 9.0 but you can download ver 9.5 if you need it for Vista. You will need one version for each machine unless you can get a site license. (I wonder if these would even be available for an old version). Obviously your cost then for 5 machines would be quite high. Personally I just dictate off of one machine (a laptop)

As for microphones I am not an expert yet I have good results with the one which comes with the program in the box. There are better ones out there yet I'm not certain if they are worth the cost. Good luck.