E800, only PIO4 IDE transfer rate?

[Sparc]

Wy not ask here?
I've just installed XP Prof. But there are errors on SCSI channel A, so I've tryed to get a 80gig Maxtor on IDE running and then figure out what's wrong with the SCSI interface.
LE chipset should have ATA66. In the bios area UDMA-2 (33MB/s) is the best entry.
And PIO4 (UDMA-0) is the only that XP can use (fields are greyed out).
What's the matter? Is no better driver for LE-chipset in XP? Or something else?

By the way - has someone the funktion of the DIL switches on the CUR_DLS available?

Thank's in advanced
Sparc (U1 3D - currently)