A friend of mine has also recommended that you keep RAM based on your Hard Disk space. If you have a 160GB HD on XP, he recommends a 1GB RAM minimum. My recommendation is that if you're not running a lot of intensive programs, which appears so, since you claim to be running on 256MB, then 1 GB should really be quite enough. However, I recommend you go for a single 2GB stick, which will be a good investment for the future. Later on, as and when required, you can upgrade RAM by purchasing another RAM stick.