I have a friend that wanted to upgrade the memory on his system 2x256mb 533 to 2x512m 667 but no matter what memory he installed in DIMM1 the pc would not post.

My question is what goes in there that gets damaged just by swapping memory sticks?

hmmm... ram sticks?? Seriously though, gotta have more info... MB make??

I was just curious about something... I thought this could be a general question( i thought all ddr2s were the same?)i dont know any specific details other than they were 2 dell sticks replaced with 2 wintecs

How about voltages? Did you increase them for the 667 sticks?