i use win 98se , and here's my story:
my pc started being naughty............ out of memory errors, apps working soooo slow. hmmm there's something going on here i thought.
after typing *temp* into "find all files" i chose temporary internet files folder and nearly fell off my chair when it opened up. i had accrued 19,100 temp files in 3 months on the net!

i pushed ctrl + a  to select all, right click on any highlighted area and chose delete from the menu. remember to empty your recycle bin too!
next up was a defragment to tidy up the harddrive and viola! my pc is happy again and so am i  ;D