I just updated my CPQ 900US laptop processor. I used an AMD Athlon-XP-m Barton 2400+ processor that is designed with a running voltage of 1.45V. Part # AXMH2400FQQ4C. This unit dropped in and booted on the first try. The running speed is 1788 Mhz, but I did boost it to 1890 Mhz. The boosted speed includes a FSB bus speed of 280 Mhz. I also have 1Ghz, 2x512 memory and the unit speeds are very noticeable over a stock AMD@1.46 Ghz. I did use a used processor. I think that the upgrade was well worth the effort.