Sylwek reckons this should be stickied:
When you buy a new CPU cooler expect your CPU to run hotter than it did with stock cooling at first but don't panic, the thermal paste you have just applied takes time to cure or burn in before heat can easily pass from the CPU to the cooling block,
most thermal pastes take 100-200hours to cure depending on how much load is on the CPU, you can use:
http://users.bigpond.net.au/cpuburn/...et.au/cpuburn/
to quicken the process
hope that stops people worrying about wasting money on a cooler which makes their CPU run hotter than usual, i know I did!