I agree. The rockhopper is way better. My friend has a '07 rockhopper sport (very stiff frame for the price). The component lineup on the '08 rockhopper is SRAM, and you get avids Juicy 3s versus the bb5s on the hardrock. Someone said the hardrock is a beefier, more downhill like frame, but ive tried one and its just dead weight. Rockhopper or Hardrock is like Frontier or Mesa (schwinn). The Hardrock is for if you like commute to work and your bike sees the trails maybe once a month, but the Rockhopper is for off-road performance. The rockhopper is mostly like stumpy, but not a race version. YOur best bet is to head to your local bike shop and ask them.
Glad i could help