hmm, i have virtually identical computer specs with yours, and tsl runs like its supposed to. i did, however, notice that you haven't tried the catalyst 5.2 drivers yet. there's a link in the sticky thread at the top for the 5.2 drivers (they're the latest drivers). give it a try and tell us if it works or not.
See the struggle of the faithless lot as they negate their time
How low to sink to the depths of their frame of mind