I don't know if this is of interest:
hda on PIIX4, hde on HTP366 udma3
kernel 2.5.8 :
hdparm -t /dev/hda 9,5MB/sec (as usual)
hdparm -t /dev/hde 30MB/sec (best so far)
kernel 2.5.9 :
not tried
kernel 2.5.10 :
crashing during boot probing hde
kernel 2.5.11 :
hdparm -t /dev/hda 9,5 MB/sec
hdparm -t /dev/hde 15 MB/sec ( never got less than 25 in the past )
BTW 2.5.11 will not compile for me if sound support is
enabled (gcc3.0.4), complaining about KERN_ERR not defined