WordPress multisite permalinks

[tamjl]

Hi there -

I'm being told that, on a subdirectory-type installation of WP multisite, the main domain's posts will be forced by WordPress to have this permalink structure if the permalinks are updated:

http://domain.com/blog/index.php/post-name/

Is that accurate...that WP will force both /blog/ and /index.php/ in there to pre-empt potential collisions with the subdirectory domains?

If so, is there any way to get index.php out of that permalink? I have hundreds upon hundreds of blog posts with links to other posts in them, all of which would have to be updated by hand, since index.php has never been an issue until now. (I can't do a search/replace because not all internal links in the posts are to other posts -- some are to pages).

Thanks for anyone with multisite expertise who can help me make sure that what I'm being told by my host is accurate.