Best way to add html 'archive'

Existing forum is well indexed

[badass101]

Hi all,

I'd like to do a bit more SEO on my forum. It's currently a fairly vanilla phpBB install with some SEO'd template changes and session ID removed.
It's indexed nicely in Google and draws some good traffic for more niche searches, although the majority of traffic comes due to it being the most important site in it's little niche and being well linked to.

I know of the benefits of making your forum have an html copy (i.e: archive) but I'm wondering how to go about doing this now I'm indexed in Google. I don't want duplicate content penalties.

Should I just add it, and block spiders from the main forum php pages with my robots.txt, therefore forcing them to index the archive?
I think this will probably lead me initially to be duplicated, but then will eventually sort itself out - or is there a better way?

Anyone else done this before?

Craig

[rogerd]

Quite a few vBulletins seem to run parallel versions - the dynamic forum pages and a static-looking archive. The archive has plain URLs and strips out all the foo-foo features. The content often isn't an exact duplicate because of pagination and content organization, but presumably there's still some risk.

From what I've observed, the archive pages often seem to do better than the forum pages; however, when people deeplink to the forum, they'll always link to the forum page itself, so sometimes forum pages (both topics and threads) benefit from deep links and outperform the archive.

You bring up the classic "dynamic dilemma" - do you block the dynamic pages (that are indexed and doing OK, if not extremely well) and watch your traffic tank while the static pages are being spidered and indexed?