Clean URLS all over the site, script changes and rewrite

I got a site with non search engine friendly URLS like ID ? bla bla - the important thing is that the title of page is in the URL, like [login to view URL] or [login to view URL] if a visitor goes to a users blog. Also I would like a meta description, which has a part from the page, unique on every page, of cause all links on the site must point to the good urls. This is no big case I think a little rewrite and changes to script would be in this job, but you will see.