Just thought it my part to let you know that Hostelbookers booking system is not 100%. I have used them in the past with few problems, but since they have joined Ryan Air my luck, and others, has not been so great.
Recently I booked a hostel in Edinburgh. They gave me a confirmation email, AND I even paid them for my room. When I arrived at my hostel they had no record of my booking. When I told them it was from Hostelbookers the woman looked at me and started apologising. Apparently they have been giving and charging for rooms all over when it is a high season without contacting the hostels. So they are booking rooms that are in fact not available and taking down deposits for their pockets. £1 to £4 a person must really add up. To make matters better there were no rooms available anywhere in the city. I have emailed Hostelbookers three times in the last two weeks about this occasion and they have yet to even get back to me.
So just a warning to all you hostel jumpers. I would suggest using hostel world, as they have the same prices. OR just go straight to the hostel pages and book. Or you might end up on the streets with no place to go like I was.