If it's an old bike, it probably has horizontal rear dropouts, which makes it a perfect candidate for conversion to fixed gear-one speed, no shifting, sounds like a step backwards, but, no,try it. If you're like many of us, you'll never want to go back to multiple gears. Checkout the Old Skool fixed gear site for lots of information about fixed gears. Also, go to Sheldon Brown's fixed gear commentary on the Harris Cyclery site. Sheldon will give you to real step by step, why and how. I ride fixed 100+ miles a week in Vermont, which is not the ideal location as it is so hilly here (I haven't seen another fixie up here). But I'm 53 and, if I can do it, well...you really ought to look into it. You might surprise yourself and save thousands of dollars not spent on one of those fancy schmancy road bikes.
If you do get new shifters, go with Campy. You won't be disappointed, though they might be worth more than your frame.