Be careful: Dragon NS 9 preferred will run fine on bootcamp but my experience is that you need a Macbook with heaps of grunt to run it effectively on Parallels.
Here's my experience. Until recently I had a Macbook 13", 2.16 Mhz processor and 2 MB ram (purchased mid 2006). This was NOT adequate to run Dragon NS 9 preferred on Parallels. When trying to train it the app just froze up. Whether this was because of lack of processing power or ram I don't know, but you couldn't get any more than 2 MB ram into the 13" or get more than a 2.16 Mhz processor. For some reason I couldn't get the machine to assign more than 904 MB ram to the Virtual Machine and thi sis not enough to run Dragon - you need a minimum of 1Gb RAM. NS ran fine on Bootcamp, but not Parallels.
Last year I got a Macbook Pro 15" with 4 MB RAM and the 2.4 Mhz processor. Still running !0.4.11. Dragon NS 9 preferred runs just fine on Parallels under this setup.
Another word of warning: The Mic input on the Mac will not work with unpowered mikes. Your Mac will default to the built in microphone without you realising it - with variable results. You must get yourself a USB headset (eg Pantronic) for decent results.
Hope this helps.