Do magnets and electronics mix?

Ever since Kurt Vonegout first wrote about magneticly suspended furniture I have been in love with the idea. When S.A.P. came out with the relaxa isolation base ($500) My interest was rekindled. My first thought was that I could make my own for about $100. The only thing that bothers me is what effect rare earth magnets will have on the electronics... tubes in particular. I can not believe it would not fowl a stream of electrons. Perhaps the exponential decay of force over increased distance is enough buffer. Any thoughts, fella's? I like the idea of zero contact under my components. I wonder how many magnets would be required to lift my 200+ lb altec vott's and what havoc that would wreak.