Hmm, I just tested my stock 750Gb 5400rpm HD with XBench, and here's what I got:
Results 59.12
System Info
Xbench Version 1.3
System Version 10.6.8 (10K540)
Physical RAM 8192 MB
Model MacBookPro8,2
Drive Type TOSHIBA MK7559GSXF
Disk Test 59.12
Sequential 136.98
Uncached Write 168.25 103.30 MB/sec [4K blocks]
Uncached Write 149.10 84.36 MB/sec [256K blocks]
Uncached Read 96.87 28.35 MB/sec [4K blocks]
Uncached Read 160.57 80.70 MB/sec [256K blocks]
Random 37.70
Uncached Write 14.14 1.50 MB/sec [4K blocks]
Uncached Write 88.44 28.31 MB/sec [256K blocks]
Uncached Read 60.56 0.43 MB/sec [4K blocks]
Uncached Read 131.69 24.44 MB/sec [256K blocks]
That doesn't seem to be much worse than the Samsung...
Polbit
Results 59.12
System Info
Xbench Version 1.3
System Version 10.6.8 (10K540)
Physical RAM 8192 MB
Model MacBookPro8,2
Drive Type TOSHIBA MK7559GSXF
Disk Test 59.12
Sequential 136.98
Uncached Write 168.25 103.30 MB/sec [4K blocks]
Uncached Write 149.10 84.36 MB/sec [256K blocks]
Uncached Read 96.87 28.35 MB/sec [4K blocks]
Uncached Read 160.57 80.70 MB/sec [256K blocks]
Random 37.70
Uncached Write 14.14 1.50 MB/sec [4K blocks]
Uncached Write 88.44 28.31 MB/sec [256K blocks]
Uncached Read 60.56 0.43 MB/sec [4K blocks]
Uncached Read 131.69 24.44 MB/sec [256K blocks]
That doesn't seem to be much worse than the Samsung...
Polbit