try changing the virtual memory
How much ram do yu have??
You don't have to keep Auto Protect on at all times. Disable it when you use a processor hungry program.
Defrag your hard disk and increase your virtual memory or the size of your swap file, as our friend has suggested above.
Start MSConfig by pressing WinKey + R, typing MSConfig and pressing enter. Check to see if any unwanted services load during startup, and if so, disable them.
If you're really in trouble, disable the GUI effects in XP and use the classic theme.
install more ram or uninstall nav
try switching off display effects and increase ur page file size. the best thing to do would be to uninstall NAV
UNISTALL NAV this suck all the memory!
try something like mcafee. it worked 4 me
do see the 30 minutes expert booklet given by digit some months ago to see some tweaks to speed up winxp