I have had a problem with serial ata convertors, or at least i think, i installed one on my Maxtor ATA133 80GB 8MB to see if it helps at all, reformatted the drive (as it didn't seam to understand the old partition tables which where standard ntfs) and restarted the system, copied some data across to the newly partitioned and formated drive and the copy speed seamed normal (no obvious increase), the next day when i restarted my system the drive didn't respond (and has now offically died).
I had also noticed tht when the system had drives being converted, the system (NF7-S) didn't shut down properly, it would power down and immediately restart again (i had to pull the plug to stop it) after which i had to reset the system (reset button) before starting the system or it wouldn't respond.
Weird!!!!!
Thats all i know about convertors i'm affraid, hope this helps
BigL