In the days of film, the most important equipment investment you could make was in your optics. Good clear lenses meant clearer images with better contrast and in some instances better color too. Photographers put a lot of value and money on their great optics. And the same remains true today. However, many people erroneously believe that they should keep their old lenses and use them with their new DSLR cameras by buying converter rings, etc. Unfortunately, this is a flawed idea.
Your old film lenses were formulated for film. Digital is a completely different medium requiring a completely different design. If you mount your film lens on a full frame sensor, you will find a significant amount of fall off on the edges; this is most evident when shooting with a wide angle lens. This becomes a little bit less obvious with a cropped sensor as you are no longer utilizing the whole surface of your lens. Furthermore, with the advent of digital cameras, manufacturers introduced a great deal of technology, most of which is lost if you are using old lenses. Specifically, things like auto focus may no longer work correctly and matrix metering may lose to center weighted metering. This is perhaps the most significant loss; proper measurement of light is probably the most important thing every photographer needs. And there's nothing that beats matrix/evaluative metering.
Although keeping your beautiful film lenses may seem like a great idea especially for your pocket book, most of your investment in that wonderful digital camera is poorly served by trying to scrimp on the lenses.