INTEL Pentium M 2.0Ghz SL7EM works greeat in Dell D600 with A16 BIOs!
I dropped this gem into my old Dell D600 by following a video on Youtube. Worked like a charm. Moving from 1.3Ghz to 2Ghz has now my old Dell somewhat still relevant. I already had the A16 BIOs update, so no problems there. From what I read, the highest you can go is 2.1Ghz in the D600. Max is 2GB of RAM and the BIOs can only support up to a 120GB HD.