HDD slow performance with no Intel Sata controller after flashing BIOS with new version (mobo= AB9 PRO)

Hi,

I'm being puzzled with my HDD performance. The scenario is like this:

Comp config:
MoBo: Abit AB9 PRO
Proc: Intel E6420
HDD: Samsung HD321KJ - (review here
http://www.techtree.com/India/Review...880-632-3.html)
2 GB RAM
etc.

Intel Controller is enabled as AHCI in bios.

When I had a fresh Windows install (and the HDD was practicaly empty,
except for windows and the HDD speed test tool) i registered
performance of 70-80 MBytes/s.

I think that my problem started after I flashed my bios to version 19
(or it could be cause by the HDD filling up) that the average transfer
rate on my HDD went to 15-25 MBytes/s . Before the bios update, I had
an Intel Sata AHCI controller in Device Manager, now I only have
Primary and Secondary IDE channel, and Standard Dual Channel PCI IDE
controller under "IDE ATA/ATAPI controllers". Trying to install the
intel controller ends with a message that no such device exists.
What am I doing wrong here? Is the HDD borked?
Help is very much appreciated.

Thank you in advance.