I am in the process of building a track with Carrera track. I have done the work to convert the track to Nincos digital system. A few thoughts: digital slot cars are fun, but not yet universal in OS, so you really need to use Scalextric on Scalextric, Carrera on Carrera, etc. Ninco says you can chip any car, and you can. It just isn't as smooth as analog. My advice old be to get a nice analog set with as much track as you can fit in your area. Running around an 8' loop is fun for about 10 minutes. The danger is in the collecting of cars though. It starts as something you do for "the kids". The next thing you know you are paying top dollar on eBay for a discontinued Fly GT40.
Here are a couple of pics of my work so far. That's the #6 Andretti car in the leadrockonsmile. Since I am working in an unfinished area of the basement, the background isn't the greatest,,,,,yet.