SONAR 8 on an iMAC

need to dual boot windows

I don't know why it wouldn't. It is a normal windows install on your own Mac box. You're not using parallels to appear to be running on windows- you actually are running windows. It should work fine. I'm running Windows on my Macbook Pro with Bootcamp and it works fine with all my windows software.

I read somewhere that Cakewalk wouldn't work with OSX Mountain Lion.  Just hate buying Windows 7 strictly for Sonar for $219.00 when I can alternative buy Logic Pro 9 for $199.

Depending on what you want to do, and how you intend to use Sonar, the computer choice does matter.  If you are strictly going to be doing live recording, and really want to use Logic, then Mac is the choice.  As has already been pointed out, Sonar will not run under the Mac o/s.  You will need the Windows o/s.

However, if you are intending to use lots of VI's, working primarily with sampled sounds, then, the issues change.  Both VSL and EW have been very straight forward stating that their libraries run better on the Windows o/s than on the Mac o/s.  The Mac simply no longer has the advantages that it used to have.  That can be hard to take for long time Mac users (used to use Mac myself), but for music production, the advantages are very much on the PC side, unless you use Logic, or Final Cut Pro, both of which, obviously, require a Mac.