I found these 2 great links showing the capabilities of Parallels Desktop(videos demo Included) and setup instructions. I hope this will answer all inquiries about Intel Mac Machine running windows OSs.

Hack Attack : Side-by-side Windows and Mac Os with Parallels

The next link is about Parallels Desktop's Coherence which allows Mac OS X and Windows fused together(Sort of). This functions enable Mac users to run Windows Based applications in OS X. Watch the video and You will Understand what i'm referring here.

Hack Attack : How to run Windows and Mac OS X apps side-by-side with Parallels

By right, I dont think that Windows viruses will go thru Mac Os since both running on different cores. But as u said, if run both side by side, we'll never know what will happen wont we?

Still, i do believe that Os X will not be infected by Windows Viruses/spywares. Else you'll see us running antiviruses and spyware prevention apps already.

Wei is referring to running windows apps with Mac OS X. Click on the second link or check out Parallels Desktop's Coherence function~!

babyk,

Running on Coherence huh? experience any lag? how's the overall performance so far? Seems good from the video. Everything is running quite smoothly..