If you love projecting, you should consider a good projector such as a Leitz Pradovit. They use 250W halogen bulbs, with efficient cooling. The benefit is much less heat cooking your slide during projection. Aspherical condenser lenses make sure that you have uniform light illumination of the entire slide. Of course, you also get the benefit of Leica lenses for the projection.
A more commonly found alternative is the Kodak Ektagraphic. Off the shelf, they produce a yellowish light, but brighter light modules are available from Kodak and Navitar. Navitar also made very high quality projection lenses for the Ektagraphics.
I would be reluctant to keep using an old 500W projector to show your slides with. The heat generated by these old machines will roast your film quickly. You can tell when the film is roasting because it will literally melt and distort in front of you. If you really keep it in the projection gate beyond that, it may even start to smoke. I found this out the hard way when I tried a Navitar super bright light kit that lacks the heat deflection glass. My test slide lasted for about a minute before it became melted plastic. Subsequently, I bought a heat deflection glass for that module.
Prolonged or repeated projection will fade the slides.
If you plan to project, try taking two of every shot. One to project, one to keep. You can scan the keepers, and show the others.