Here's what I have, a great value:
COOLER MASTER Hyper 212 Plus
Newegg.com - COOLER MASTER Hyper 212 Plus Intel Core i5 & Intel Core i7 compatible RR-B10-212P-G1 120mm "heatpipe direct contact" Long life sleeve CPU Cooler
Keeps my i5 at just under 30c at idle, and 47c max through 6 hours of Prime 95
Here are some good articles for you:
Intel Core i5 750 Overclocking Guide (ASUS P7P55D)
Intel Core i5 750 Overclocking Guide - Introduction
Efficiency Explored: What's The Perfect Clock Rate For Your Core i5?
Efficiency Explored: What's The Perfect Clock Rate For Your Core i5? : Hunting Down The Perfect Clock Speed For Core i5
Overclocked On Air: Intel's Core i5-750
Overclocked On Air: Intel's Core i5-750 : Maximizing Core i5 Value Through Overclocking
Good luck, i5 is a great overclocker, but a simple baseclock change to 160 with turbo will give great overclock with the advantage of good power consumption. A Guy
P.S. Make sure your case is wide enough for this. 8" should do it, unless you have a side fan. What case are you using?