Is there a good software program to convert
 

...dynamic php pages to static html pages?

but you would just end up with static HTML pages which suck... why bother? Are you really just wanting a site downloader?

No. It is my understanding (and it appears to be true) that SE's do not crawl and list dynamic pages very well but do crawl and list static html pages very well.

thats an understanding from 3+ years ago... they handle it pretty well these days but I always use mod_rewrite just in case so that all my dynamic display.php?id=123123 looks like this display-123123.html

Well...in my case only a few pages were crawled and listed and this has not changed even though the SE bots have recrawled multiple times. There should be hundreds of pages listed but there isn't. Does the mod_rewrite get all or most of your pages listed?

Use mod_rewrite.