you'd probably get a better deal out of a 5770, about the same performance as a 4870, but most are still close enough (see netkas' forums for successful models, and roms) to the reference design they are being successfully flashed with modified apple roms, it also uses only one power cable vs the two the 4870 uses. I've heard the 5770s are quieter (and use less power for the same level of performance) than the 4870s. If you flashed it to mac, you wouldn't need to switch cards, but you could if you wanted to, a dvi switch is probably the easiest solution.