Andreas_Delgado - 1:14 pm on Mar 21, 2011 (gmt 0)
Do the following:
1. Remove from google index and cache all pages with low amount of original content (you can do it in webmasters account)
2. Block them in robots.txt
3. Resubmit your sitemap
The Key is to remain only quality content on your website!
You'll be surprised very soon. Good luck)