I can't Say for sure 100%, but it think it will work. No one has gotten back to me from dell. If it doesn't work, i will pay for return shipping and return credits? Thats the best i can do.
Ok i did a little research and found the 667 is a faster speed. they will fit but i need to talk to dell t0 dell to see if they will work. I will get back to you. And thanks for asking.
I'm waiting on Dell community for a reply. Also the 512 will work in you machine, pc2-4200s is the same as DDR2-533. I goggled it as (what is pc2-4200s)