After wandering around for two days I realized that SATA drives are supported
by the latest kernel builds (2.6.9) and manage to make my Dell Dimension XPS
Gen 3 work with linux (Fedora 3, gentoo, having problems with Suse network install and the on-board card (not solved yet) and tomorrow trying Mandrake 10.1 for completeness sake
).
The trick part is with the BIOS for the Intel chip-set 925X you need to disable the default installation from Dell (RAID) make the drives plain SATA and change the SATA options on the BIOS to Autodetec RAID / ATA, once you have your SATA drives out of the ugly software RAID of the BIOS they will be recognized and installed in /dev/sd(a,b,c...) as normal SATAs and you can try your favorite distro.
I'll post a full report on the forum later with thanks to all that helped.