That is a cheaper way to go than buying Apple's upgrade to the 20 gig and gives you a faster drive. Also, all four third party drives can be formatted with Apple Hard Drive Setup utility and be designated Startup Disk. The internal IDE interface is too slow. I've heard you can double the speed of ATA drives if you create a striped array. The ATTO disk benchmark was run using Express-Pro Tools 2.3 benchmark test with 8MB maximum file size and system disk cache disabled.
Sustained Rate is displayed in the charts.
Peak rates can be impressive but do not reflect typical drive performance.