Gunther,
I really depends on what you will be taking pictures of, and what conditions the picture taking will occur in. Most will say that the kit lens is a good value giving you a wide angle to moderate telephoto for $100. Most will also recommend the 50mm Mark II f1.8 for an additional $80. The 50mm is incredibly sharp with a wide aperture for those low-light pictures without a flash. I use this lens for all of my paid portrait work. I bought the first two, and rounded out my collection with a Sigma 55-200 DC lens. The Sigma picks up where the kit lens leaves off giving me a telephoto effective range of 85-300. Total cost of the camera with the three lenses was about $1200.
I find that
www.photosig.com is a good place to look for lens quality. If you go to the photo tab, there is a link on the left to search by lens. Click it and the largest list of lenses you have ever seen will appear. Choose the lens you are looking for, to launch a gallery of photos taken with that lens.
www.pbase.com is good as well. Use the search feature to search for the lens you want.