MacBook Pro (the last revison before the unibody ones)
I'm a hardcore PC guy. Started on a 386DX2 66MHz with 2MB RAM and a 120MB hard disk. Been tinkering with them and pulling them apart ever since.
Decided on a MBP as my aging Sony VAIO was slowly falling apart. Got a really good deal on it (cheaper than similiarly spec'd Sony) figured if I really didn't like OSX, I'd just use XP on it thanks to the Intel processor and Bootcamp.
Played around with OS X for about a week. Installed a bootcamp partition ready to install XP. Another week later, I format the entire disk to reclaim the bootcamp partition and do a fresh install of OS X -- I was hooked.
I still have my E6750 desktop PC and I think I always will have a desktop PC, but I will always buy a Mac for a laptop. It suits my workflow perfectly and now I'm enjoying the best of both worlds!