I want to preserve my pagerank. Should I not link to other websites?

Some of the most popular, highest-ranking websites have hundreds of links to other sites without reciprocal exchanges. The one thing they have in common is that they're linking to sites that offer quality, relevant content of which they know transfers value to their pages. Yes, you spill some pagerank when linking out to other sites and pages, but if you do it with the intention of giving your visitor another valuable resource, you've just enriched your page. Any traffic you lose to this other page will be made up in the long run due to your page having more value. Google recognizes this and sees relevant, helpful linking as a bonus. If your pagerank suffers, you'll live. Those that pay to close attention to pagerank should realize that the information present in it is already outdated. Instead, pay attention to your traffic and conversions.