I have a question about DDR Memory compatibility. Hope someone here can help. My PC has Samsung 512 MB PC2700 DDR memory. It have been running fine since I built it a little over a year ago. Last week, I tried to add 256 MB of Kingston Value Ram. Immediately, system did not work properly. It took itself 3 times to boot up (it boots, restarts booting and restarts booting before boot up). When computer is running, it suddenly rebooted itself (again took three tries) when I closed one IE window. Couldn't figure out what was the problem, I tried switching the slot position of two memory sticks and there was still problem, though not the same. Last, I tried taking out the Samsung memory and leave the Kingston memory alone, it looks fine ( I did not test long enough to know for sure). So my guess is that those two memory sticks are not compatible. Since memory is so cheap, I really want to add some additional memory just maybe this can improve my execution performance. Obviously, I'm worried that I'm not able to add any additional memory. Anyone has any advice? Thanks.