For some with lagging performance I might recommend more RAM memory. With you saying you have a 40 GB HDD you most likely have a basic comp with 128 megs of RAM. If you can expand this to 512 or even 1 Ghz if your motherboard (computer) will support it. And also, only if you have WINXP as Win98 will not recognize it.

Also I might also recommend shutting down any unnecessary background programs you may have running. Be careful but only you will know what you need and Antivirus is one you need.