Don't worry, first test the generation and frequency of your memory with the test software, and pay attention to the number of memory slots displayed by the test software. If you have it, go to the market and buy one1g. When you come back, unplug the original 256 and change it to 1G, or you can take the computer to the place where you sell memory and ask them to change it for you. Just watch. If the test software shows that the number of memory banks is two, buy a memory bank of 1G and plug it into another free memory bank. As for the 2G memory slot, I personally don't think it is necessary at present. You should match 256 with 1G first. Of course, if you really want 2G memory chips, then buy two 1G of the same model with two memory chips to form a dual channel with better performance. Test software: CPU-Z, if you still don't understand anything, add me Baidu hi!