In real life few SATA drives are any faster than PATA.
and the Diamond max 9 isn't one of them (it is a good solid HDD though ... it should last a few years longer)
I think you misunderstood the specs
Maxtor DiamondMax 9 160Gb
Performance
Drive Transfer Rate: 133 MBps (external)
Seek Time: 9.3 ms (average)
Average Latency: 4.2 ms
Spindle Speed: 7200 rpm
The 100ata bus is for CD/DVD drives ...
the 133 uata is backwards compatible and CAN be used for RAID (but not HAS to be) - and will be enabled/disabled in your BIOS. As will SATA as Primary options.
MotherBoard
http://www.asus.com/products4.aspx?modelmenu=2 &model=175&l1=3&l2=12&l3=30&l4=0
South Bridge:
-2 x UltraDMA 100
-2 x Serial ATA, RAID 0, 1
Promise 20378 RAID controller:
-1 x UltraDMA 133 support two hard drives
-2 x Serial ATA -RAID 0, RAID 1, RAID 0+1, Multiple RAID
Generally CD/DVD use 40 wire (ata) ribbon connectors ... your HDD should be connected to the 133 using a 80way ribbon (uata)
CDs and hdd should not be connected on the same bus as the slowest device sets the overall speed.
Also 40 way ata does not support cable select ... so on the 100 bus you'd need to config master and slave (Csel is the default out-of-the-box) to get things going.
buy a 80way ribbon ... and give it a go
Sata is the new standard ... so when you eventually upgrade it will probably fit your new machine
other than that I'd be surprised if you could see any difference
You already have