[Scenic-D 815E D1214] large drive setup

[kennylands84]

I've installed a 250GB Seagate drive in my old Scenic i815E, first flashing the bios to version 1.13 - the bios sees thge 250gb drive ok when set to AUTO detect. There are a couple of other bios setting (UDMA restriction and large disk handing = dos/other) that I'm not too sure on the correct setting.
XP SP2 took an age to see more than 128gb, and I had to remove the Intel application accelerator/ATA-100 chipset driver that came with the Scenic. After removing these and using Seagate's DiskWizard, the drive formatted on and I cloned the old primary drive to the new Seagate drive.
The problem I'm having is that the drive seems to be very slow. The PC seems to pause on disk reading, if that makes sense.
Does anyone know what the correct bios settings and windows xp pro sp2 set up should be to get the most out of the new drive ? I've tried using HD Tune and that reports that the seek time is out at 27ms (double what it should be) and the tfr rate averaging 57mb/s again about half what it should be.
Any help gratefully received.