You can put 2 x 1GB sticks in according to Crucial, but from what I've read, some people say it will accept up to 2 x 2GB, but it will only address a little over 3GB of it because it is a 32 bit operating system. Get the exact same memory speed for it though (DDR2-667 PC2-5300). It will not accept DDR2 1066 memory.