Should I buy a MacBook Pro or a cheap PC laptop when all I need is a simple PC system?

I am a lifelong Mac user. However, I am starting to work at a new location whose software is only PC-based. I need to be able to connect from home to the specific PC software, and therefore need “a PC”. I currently have a PowerBook G4 running Tiger, and I am still quite happy with it. Virtual PC is really, really slow, so I was debating whether to invest in a cheap PC or bite the bullet and upgrade to a new Mac. Any suggestions pro or con, and specific ideas for a cheap PC (if that is your suggestion) would be greatly appreciated.