I have a Dell system currently with 512x2 of PC2-4300 DDR2 memory. I'm looking to upgrade with another 1gb (512x2) set. Looking around i see that both 4200 and 4300 are DDR2 533. Checking newegg there is only 4300 one that matches this and it's $118. While there are 12 4200 items for around $70-80. I thought I remembered reading somewhere that if you put slower memory in with faster memory, the faster memory will underclock to the slower memory's speed. So obviously the difference in speed would be small in comparison to the current speed. So I think the answer to my question is yes, but is it fine to use the 4200 memory with 4300?