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Get SATA 2. The bus speed is faster (1.5 -> 3 Gb/s) but more importantly you also get Native Command Queuing (NCQ) with SATA 2. If you're doing a lot of random disk activity then NCQ can make a substantial difference to drive throughput.
 
Thought I'd clarify with some research I just did. First, there's no such thing as SATA II (what 3.0 Gb/s is commonly called). So when looking at hard drives, don't look for "SATA II" because a 3 GB/s drive may just be labeled as SATA. Second, the tech specs show the MPs support the 3.0 GB/s protocol, so yes.
 
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