Shameless double post.
I know you wanted something from Microcenter, but may I suggest something from Newegg?
long ass linkThey don't have silver thermal conductors, so copper is the runner up.
You'll have to set the specifications yourself, sorry. There is a little more to than just picking out a heatsink.
You will need to indentify the CPU socket you're using (Since you're using a AMD Phenom processor, I am going to assume it uses AM3). You will also need to see if the heatsink you found will fit in your computer (Usually because RAM or the walls of the case will cause problems with the installation.)
Lastly, you will need to check what kind of pins your CPU fan uses such as 3-pin or 4-pin and see if your current fan uses the type of pin or your power supply has a spare cable tangled up.