ok ok, it's NOT for me, it's for the missus... installing windows ME on a compuetr with a DANM old hard drive (WD caviar 21200 1.2gb, amde 1994 i think) now i also tried win98, with similar results in that it crashes. not running for moer than 10 minutes on average (onyl boots completely one in 3 goes...) DMA was always off on the drive, and the PIO mode in the bios was defaulted to 4. i changed the mode to 0, and things *seem* to be working now. I was continually geting BSOD'd and erroros about USER.EXE, GDI.EXE you know, the regular crowd.

So, can anyone comment on the change in PIO mode and the apparrent success?

I researched the ATA spec, including the PIO modes, rather throughly a few years ago when starting a book about PC Peripherals (that never got finished due to major staff changes at the publisher, and rapid changes in the state of the peripheral art). The major difference between mode 0 and mode 4 is the data transfer rate. Mode 0 is much slower because it includes more thorough handshaking between the FDC and the drive -- but is also more accurate, as you've found.

My opinion is that you've solved the problem in a creative way, so don't worry about it. As you probably know, Linux has defaulted to PIO since day one although many distributions now seem to switch to DMA for the slight speed increase it sometimes gives.