SATAII with VT8251

I recently tried to install a WD5000DSRTL 500g Sata II hd on my A8V-X mobo. Mobo is suppose to be SATA II capable. The BIOS sees the drive, while installing Windows XPw/SP3 I installed the raid drivers (F6) and windows saw the drive, allowed formatting and started installing OS. However, took extremely long to copy files, and many tries. Kept saying couldn't copy numerous files. Once a good copy was installed system would not boot. Just a flashing cursor. After several attempts, I jumped pins 5 and 6 to back the drive to 1.5g. Now the drives works great. There is no mention in the manual indicating to make any changes on the board to get it to function properly with SATAII mode. The SATA driver is VT8251. Any ideas on what could be going on. Bios is set for sata/raid mode. This is the only HD attached for now.

A8V-X mobo
AMD 4000+
2gig Memory
Windows XP with SP3
500gig WD Sata II
480w power supply.