I currently have a Dell Dimension E510 with a Pentium 4 640 CPU, 3GB RAM, Windows XP. My computer has been making a buzzing noise for the past year or so and I'm guessing it's either the CPU fan or the Power Supply fan. I'm replacing both this Christmas and I need some help doing it. For the power supply I already have one in mind and I already have a CPU fan in mind too (http://www.newegg.com/Product/Product.aspx?Item=N82E16835106087). I was just wondering how do you install a new CPU fan, are there any other things I need to buy alongside my CPU fan, and what criteria should I look at when choosing a fan?