Re: How many links do I need?

The higher PR (and TrustRank), the better.
The more, the better.
The more related to the content of your website, the better.

Sebastian suggests to read this website: http://www.seobook.com/ - but
he also provides some nice content:
http://www.smart-it-consulting.com/article.htm?node=163 .

And there are many, many postings with questions (and answers) similar
to your question. So please read them, too.

Tobias