Hi,
I have to agree with J-B
256MB is hardly enough - your machine must be running extremely slow.
I suspect that it is freezing at times too ??
If you want to upgrade your RAM ( which will make a big difference) try scanning your system from here:
RAM Memory Upgrade: Dell, Mac, Apple, HP, Compaq. USB drives, flash cards, SSD at Crucial.com
Crucial Scan will tell you the maximum RAM that the motherboard can support.
It will also tell you what is compatible and give you an idea of price.