Which laptop is the better buy, this $2000 Mac Pro, or this $779 ($750 on Amazon)?

If you don't have specific program(s) which will run only on Mac, I would recommend you to go for the Acer. And another issue with the Acer, it's O.S is Windows 7 Home Premium 64-bit (as mentioned on newegg), I would suggest you to ask for Windows 7 ..... 32 bit not that 64 bit, since most programs run on 32-bit platform.