Thank you for those links, although I'm still having the same problem. I looked through all of the ones listed, and they each have one of two main flaws:
-They use 240-pin desktop RAM rather than 200-pin laptop RAM
-They don't show as supporting the 667MHz FSB that the T5850 uses
The only one I've found that seems to support everything I need is this:http://www.orbitmicro.com/global/socket
But the port lineup is pretty poor.
Well, I can agree that the Jetway J9F2-EXTREMER3-LF seems to be using 240pin memory (that is not normal for motherboards that use mobile processor, so I didn't catch that). But the others should be just fine.
You really need to check the manual for each motherboard to rule them out. I just checked the MSI board that I linked to earlier (IM-GM45-D). According to the manual it supports socket P processors running in either 667, 800 or 1066 FSB. And it supports DDR2 SO-DIMM (200pin) running in 667 or 800 MHz. So I'm not sure where you are looking?