|Since you have given no information about either the hardware specification of your system, or the configuration of the network environment it is operating in, just how are we to diagnose whatever is causing your slow performance.|
The only bit of info in your heading indicates you are running XP on a system with only 256mb of ram.
If that is the case then that may be a major part of your problem. XP uses most of 256mb ram just to run itself without doing anything. Once you start opening files and running progs such a system will bog down.
First step. Get more ram
Goin' Fishin' (Some day)