I found this thread helpful for my HK visit last week (Nov 2006).
Yes, World Sports Co is a good small sized store. It looks like a family run business, and the staff was indeed helpful.
The other shop I liked was the chain Chamonix Alpine Equipment – their new store is located just round the corner from World Sports Co (a corner unit – I don’t remember the street). They had a promotion where if you spend above HKD300, everything is 20% off. I ended up going to the shop 3 times, each time enjoying the 20% 
Pro Trek along Nathan Rd, near Mong Kok MTR is another shop I visited. More of the same type stuff (different brand) from the above 2 shops, and I had already purchased most of the equipment I wanted from World Sports and Chamonix.
Cheers,
Jack
(Singapore)