I have an old Dell optiplex GX240 on Pentium 4 1.8Ghz and 256MB Ram (or was it 512MB). It's still in working condition but it's getting slow for me and i wanted to optimize it. I just want that old box to be usable even for simple desktop use (email, surfing, chat). I also have to note that my parents prefer use it over a laptop for some reason. Treat it as a "box-type netbook".

unlike the other threads that they all prefer sending away or use as file server, firewall and that, i am looking for suggestions on how to keep it usable as the main PC. any suggestions? OS perhaps?