Hi
Have you run an anti spyware app or run the av (and update it first) lately?
Virii and spyware can make a system crawl, if you didn't know.
Another thing is that 256megs ram is a fairly low amount, I consider 512 to be right in the ballpark for older apps/games and any browsing use. 256 will do for most general computer/browsing use save for video editing of any sort.
As well, if you have a dialup internet connection, it will always seem slow.
Some thoughts for you.