This is something I was wondering before - why the copy operation on my home server is slow. So I used HD Tune to test th drives and got a surprise result (read testing only):

WD 160GB internal SATA:
Min: 1MB/s
Msx: 2.9MB/s
Ave: 2.7MB/s
Access time: 13.6ms

Intel 80GB SSD internal SATA:
Min: 106MB/s
Max 197.2MB/s
Ave: 171.8MB/s
Access time 0.2ms

Seagate FreeAgent Desktop 500GB USB2.0
Min: 10.4MB/s
Max: 29.8MB/s
Ave: 22.7MB/s
Access time: 21.4ms

Seagate FreeAgent Go 160GB USB 2.0
Min: 13MB/s
Max 29.8MB/s
Ave: 25.2MB/s
Access time 16.8ms

What could be wrong with the internal WD SATA drive? I know SATA can be a bit faster than this -actually the same Intel 80GB SSD on a HP Mini Note show similar good results in both machines so I know the SATA interface on this desktop is working ok.

Any ideas?