Absolutely. What they said x3.
My benchmarks showed that even a 4 year old small SATA Western Digital drive gathering dust in an old PC was almost 2x as fast as the stock drives Apple is shipping. 😡🙄
Just don't do it. Buy the single 320g and replace that IMMEDIATELY with either a Hitachi 32-Meg Drive (make sure acoustic Management is off), a Samsung SpinPoint 32-Meg Drive, or one of the new Western Digital 320-Gig Platter Drives (NOT the Energy GREEN drives).
You AND your Mac will thank you for it in the morning 😀