As a rule, you can recommend, not force, a browser to cache, or not cache, a page. Most browsers will listen to the "Expires" Header:
Expires: Fri, 30 Oct 1998 14:19:41 GMT
And the more recent (HTTP 1.1) "Cache-Control" Header:
Cache-Control: max-age=3600, must-revalidate
To sort these things out. Check out How (and how not) to Control Caches for more on this.

----Asim, known to some as Woodrow.