THE COLD HARD TRUTH.
Okay people, let's face it. Virtual PC is garbage, if your doing actual work in a business environment, and they DO NOT USE Mac software or hardware, THEN WHAT GOOD WILL YOU USING Mac SOFTWARE OR HARDWARE DO? There is no Visual Studio for the Mac, nor many of the Windows only programs that are required in a business type setting, thus the reason mac's don't fit in so well. Sure they connect no problem, and play nice on the network, but they don't run the x86 software your company is using, and Virtual PC is not up to the task of running anything. Your better off finding OS X native alternatives (if your company will allow this) or using a Windows machine to do your Windows work.
a bargain-bin PC will blow away your emulation of Windows (until Microsoft eventually releases VPC 7...then we'll see).
Summary: VPC is bunk. Your money and time would be better invested in using actual x86 hardware and actual versions of the software. Use the Mac for personal computing, but it looks like your professional work will have to be relegated to a PC for the forseeable future (CMON VPC 7!).