SEO guy, what does "mod_rewrite" mean for sites that are hosted on windows platforms?

Since we are hosting our own forum, it never occurred to me search engines could index the postings.
They can probably index the static forum links, but not the actual postings which are dynamic. Any thoughts?

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Joel Katona
Trendmetrix Software
SEOStudio.com
Search Engine Optimization Software SEO Studio: Link Popularity, Keyword Analysis, Ranking and Submission