I'm forced to live in a dual world--both PC and MAC. I have a high-end G% with Dual 2.7 processors, 8 Gig of Ram, and a 256 Gig Hard Drive. I also have an older G# with an 80 gig Hard drive and a HP Pavilion, which I use exclusively to run my bookkeeping software.
After several weeks of running all three side-by-side, I am amazed at how much both macs out perform the PC.