yeah, to reiterate what was said earlier, type "classical techno" or "classical remix" in your favorite file-sharing program and you should come up with something. Also "Beethoven remix", "Mozart remix", "Tchaikovsky remix" etc. etc. By doing this I've found a great trance Für Elise, a nice Moonlight Sonata, (my favorites) a Pachalbel's Canon and Vivaldi's L'inverno. But you also come up with some real crap too, like there's this one piece of a Mozart piano sonata that's not transformed at all except that it has a techno-ish drum track overlayed. (Somebody got really creative with that one.)
Also -- this is a really great track! -- if you know the track "Clubbed to Death" by Rob D. (from the Matrix soundtrack) it's essentially what you're talking about with the Enigma Variations by Elgar. Very beautiful piece to begin with, and wonderfully transformed into a pulsating techno-ish track by Rob D.
Also William Ã?rbit recently came out with an album completely of classical tunes played on his synth. Sometimes it's very hard to tell that they're not being played by full string orchestras! Anyway, there are quite a few remixes of these tracks (particularly Adagio for Strings by Barber). Search for "William Orbit Adagio remix" etc.
edit: guess: hhc=happy hardcore (never seen the abbr. before though)