Why would drive run at UDMA33? (Segate 80GB)

[JacobRhoden]

Hi,

I have just purchased a new 80GB drive, howerver i noticed it is running 
significantly slower than my current 80gb drive. 

Dmesg says this:
  ad0: 76319MB <ST380021A> [155061/16/63] at ata0-master UDMA100
  ad2: 76319MB <ST380011A> [155061/16/63] at ata1-master UDMA33

Why is one running at udma100 and my new one running at udma33? iosys reports 
it as 4 times slower! Is there any special tuning or kernel option i need to 
set?

The segate website reports the following details aobut it:
  Model Number:ST380011A
  Capacity:80 GB
  Speed:7200 rpm
  Seek time:8.5 ms avg
  Interface:Ultra ATA/100


Jacob Rhoden            Phone: +61 3 8344 4478
ITS Division            Email: jrhoden at unimelb.edu.au
Melbourne University   Mobile: +61 403 788 386