PowerColor's new HD 6870 PCS++ comes with massively increased clocks out of the box which makes it roughly as fast as GTX 560 Ti or HD 6950. With a reasonable price increase of only $10 over the reference design, the card does not break the bank either, it is actually a worthy opponent to NVIDIA's GTX 560 Ti considering price/performance.
Slow computer got you down? Maybe a hardware upgrade should be in your cards, if so this guide to the Fundamentals of Upgrading a PC is an invaluable read. PCSTATS Tips