You can likely buy and install a firewire (Sometimes called 1394 or 1394b to avoid copyright on the term Firewire) card for your PC for pretty cheap.
If you plan on using Phocus 2, I'd look to have at least 4GB of RAM (the more the better), an ok processor, and a good to very good video card. Phocus 2 pushes a bit of the processing power onto the graphics card so having a better card can speed the program significantly. Also when using an earlier version of Phocus with an older video card (Nvidia 7300GT, maybe?) Phocus had a few glitches (all the images would go blank, live view would freeze up) at the recommendation of Hasselblad we upgraded to a better video card and haven experienced problems since. Hasselblad has been really good on their release notes for software on their website. The release notes say exactly what is needed (including the issue with the video card that we had.) Other than that just make sure you have a huge honkin' hard drive to store your files.
If running windows, try to make sure you have a 64bit version of windows running (if your hardware supports it.) It's not required but Phocus will make better use of what you have under a 64bit OS.
If going to Mac, the low end MacBooks and MacBook Air do not have firewire so you'd have to go to the MacBook Pro, iMac, or MacPro tower. I'm pretty sure even a Mac Mini would work but it may not be the fastest think in the world
Enjoy the new camera, happy shooting!
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~K