You can only use Parallel, and not VMFusion to run moi, because VMFusion does not emulate DirectX.
At least the last time I checked (there might have been an update).

I would download the latest version of parallel, and install the RC of Windows7. This windows versionis 'free' until next spring, which gives you enough time to see if you like it. I can't remember how long the parallels trial runs for, but it should also give you enough time to try before buying.

I have run Moi under parallel on an octocore macpro. There is a little time offset when you navigate the view, but otherwise it works fine.
Also there is always the option of using bootcamp, but I think it is better if possible to just run moi under Windows and do rest in OSX, if you are used to working in the later.
Good luck