PC Club is a decent store when you're looking for some harder to find computer components. In terms of cases, power supplies, cable adapters, etc, they've got a better selection than the big name stores (such as Best Buy or CompUSA). However, they also tend to be more expensive than online retailers.
I'd recommend using PC Club just for cheap parts, or parts you really need to have soon (fried power supply, etc.). Otherwise, stick with different online retailers - you'll end up saving in the end.