Slow SATA drive problem (affects 2 of my 3 drives)

Hello forum friends, first time poster here.

I recently built the following HTPC:

Motherboard - Gigabyte GA-E7AUM-DS2H with integrated Geforce 9400
CPU - E5200 wolfdale, R0 stepping
Memory - G-skill 4 gb ddr2-800
Hdrives - Three samsung spinpoint 1.5tb F2EG 5400 rpm SATA
Optical - Sony optiarc dvd/cd burner
Case - Cooler master sileo 500
PSU - Rosewill rp500-2
CPU cooler - Arctic cooling freezer 7 pro
OS - Win XP

Out of curiosity, I downloaded HDTune 3.10 and HD Tach to see the data transfer speed of my hard drives.

One registered appox 90 Mbytes/sec avg speed but the other two averaged only 7.5 Mbytes/sec. - less than 1/10th as fast. I get basically the same results every time I test them and I cannot understand why. Anyone have any ideas?

I would just like to understand what the problem is and how I could correct it as transfers to and from those drives are atrociously slow.

Thanks,
David

Thanks for your reply. Unfortunately, one of them has about 1TB of data on it already.

Thanks for your reply, Jim_L9. The three drives are connected to SATA ports 0, 1 and 2.

My understanding is that ports 3 and 4 on my MB are only active for RAID/AHCI setups. I have not installed the AHCI driver for Win XP or a RAID driver (operating in IDE mode) so I don't think I can use them.

I am seriously considering installing Vista so I will have the AHCI driver and can use those ports. I don't currently have a floppy drive to do a third party driver install under Win XP using F6 at boot up (but I digress).