After vBSEO-ing, what happens to existing posts?

I have a vB with over 1 million posts. This thread seems to imply that I might take a 'hit' if I install vBSEO now: SitePoint Forums - Have you installed SEO scripts to your board? Has it made a difference?

Can you clarify what happens to my existing posts and rankings?

Thanks!

ETA

I just noticed something else...in the link above, I simply pasted the URL of the thread, but your board changed it into the "link with text" you see above. Is that a vBSEO function?

This is what I actually pasted above...

Code:

http://www.sitepoint.com/forums/showthread.php?t=350858&highlight=vbseo

Hi Kat!

The existing posts and pages are 301 (permanently moved) redrected, allowing their exsting ranking to pass to the new, re-written URLs.

The 'automatically grab page title of links' feature you have noticed is indeed a feature of vBSEO 2.4.5.

All sites will take a hit simply because the showtopic.php?t=1234 URL's will drop out of google, and it will take time to get re-indexed with the new /topic-title-123/ style SEO'ed page urls.

Using 301's, your page rankings and old pages will redirect to the new page, so you won't loose page rank, nor will old links suddenly turn dead.

just the count in google may drop at first.

and yes, the topic title in pasted links is a vBSEO function (one of my favorites)

its one of the best features i like actually. no need to encode in [url=xyz tags now..

*waves hi* to Acers

* waves hello *
hehe