Um, are you aware of what Boot Camp is? It's disk partitioning software and drivers. When booted in Windows, a Mac is a Windows PC, comparable to any other PC with the same components, only better designed and with cleaner drivers.
I'm not buying that an i7 iMac (coming soon) or an eight-core Nehalem Mac Pro aren't up to your "performance-level requirements."
Sure...for twice the price. Why would I want that? Macs will never be price/performance competitive. I used them for over a decade. We can spank a Mac on every graphics, ram, disk spec and then some for far less.
I run highly graphic software in Parallels and have never had a problem so I have no idea what you are talking about? INHO it runs faster on my MacBook Pro than it did on the Dell before it died.