Xbench help from you

Below is from Xbench 1.2. Same set up as above - Booted from an external 180GB 7200 Hitachi drive in an OWC Mercury Elite Pro-AL 400/USB2.0/1.1 case. I don't use Xbench 1.2. I still use 1.1.2. 1.2 varies way too much for me to put much faith in it.

Disk Test 45.92
Sequential 59.63
Uncached Write 71.75 44.05 MB/sec [4K blocks]
Uncached Write 57.73 32.66 MB/sec [256K blocks]
Uncached Read 44.18 12.93 MB/sec [4K blocks]
Uncached Read 75.82 38.10 MB/sec [256K blocks]
Random 37.34
Uncached Write 12.88 1.36 MB/sec [4K blocks]
Uncached Write 95.96 30.72 MB/sec [256K blocks]
Uncached Read 98.11 0.70 MB/sec [4K blocks]
Uncached Read 112.30 20.84 MB/sec [256K blocks]

Sorry - forgot to follow up, but seems you've got plenty of data. On XBench 1.1.3 I get:
Results 94.31
System Info
Xbench Version 1.1.3
System Version 10.3.8 (7U16)
Physical RAM 512 MB
Model PowerMac10,1
Processor PowerPC G4 @ 1.25 GHz
L1 Cache 32K (instruction), 32K (data)
L2 Cache 512K @ 1.25 GHz
Bus Frequency 167 MHz
Video Card ATY,RV280
Drive Type Maxtor 6 B250R0
Disk Test 94.31
Sequential 76.81
Uncached Write 79.50 33.14 MB/sec [4K blocks]
Uncached Write 79.42 32.52 MB/sec [256K blocks]
Uncached Read 63.51 10.05 MB/sec [4K blocks]
Uncached Read 89.63 36.21 MB/sec [256K blocks]
Random 122.14
Uncached Write 626.65 9.40 MB/sec [4K blocks]
Uncached Write 103.56 23.36 MB/sec [256K blocks]
Uncached Read 99.33 0.66 MB/sec [4K blocks]
Uncached Read 87.49 18.01 MB/sec [256K blocks]