PT Boats is quite demanding on the computer, so I'm surprised I haven't seen any comments on that aspect. So I thought I might start with what I've found to date.
My system is: Intel Pentium D 3.00GHz, ASRock 4CoreDual-VISTA motherboard, 2Gb DDR2-533 RAM, Gigabyte ATI HD 4850 graphics card. Not a great system, although up till now it's been adequate. The biggest limiter I have is the motherboard, it just doesn't do the job, and that's reflected in low fps and middle of the road graphic settings.
Much as I would like an Intel i7, it's just not possible at present. But I've come up with a system upgrade that will cover me for the next year, and let me play PT Boats as it should. For just $312.00 (Aus) I can get a Intel Core 2 Duo E8400 3.00GHz, Gigabyte G31-M motherboard, and 2 Gb DDR2-800 RAM. I'll keep my existing HD4850.
That'll make it hum!