Hmm, never stayed in the marlborough. I stayed in the abbey hostel near backelors walk, which is on the other side of the river dead opposite the temple bar.
Theres a really cool bar in the middle of the temple bar in front of like a square 'thing' with a cash point. Its great in there, theres an upstairs and a downstairs. Upstairs they have live irish music, with a dancer and everything, icluding a man on a stall with one of those drum things. Its a great place. I loved dublin!