How do you expect to build the PR
of your internal pages if you make the links nofollow?
How does Google handle nofollowed links?
In general, we don't follow them. This means that Google does not transfer PageRank or anchor text across these links. Essentially, using nofollow causes us to drop the target links from our overall graph of the web. However, the target pages may still appear in our index if other sites link to them without using nofollow, or if the URLs are submitted to Google in a Sitemap. Also, it's important to note that other search engines may handle nofollow in slightly different ways.
What are Google's policies and some specific examples of nofollow usage?
Here are some cases in which you might want to consider using nofollow:
Untrusted content: If you can't or don't want to vouch for the content of pages you link to from your site...
- Webmaster Tools Help Google
You don't vouch for your own site?
What you are asking about is PageRank sculpting.
- Matt Cutts' blog
What are your views on PageRank sculpting? - GoogleWebmasterHelp