That's pretty much it on IE6 (see this info from Micr*s*ft).
The process varies a bit on FireFox depending upon which version you are using, but it is essentially the same idea. On version 2, click "Tools" -> "Clear Private Data", and mark the checkboxes as desired.
That said, I have found that, on occasion, FF has needed to be closed and re-opened after doing this in order to completely clear the cache. In some instances, merely reloading the page via a ctrl-F5 keystroke, in IE and FF, or ctrl-shift-R , in FF, will be sufficient as it instructs the browser to reload the page and override the cache.
Actually, all you could ever want to know about clearing your cache is available here!