lol I got some mobo and graphics card lol.....and yeah when my computer didn't POST or anything...no beeps no nothing thats a good sign that the processor isn't working...in my case I popped off the heatsink and guy who replaced it put thermal grease on TOP of the stock heatsinks thermal pad..and he globbed it..got all over the connectors and shorted them out..luckily the CPU survived but it corrupted the boot sector of my HD and had to format.
Do you happen to have the MSI KT6V motherboard with that KT600 chipset? Cause if you do then you should have had that D-link bracket with 2 extra USB ports come with it. It also has 4-led lights that light up in a specific order and the color of them are either red or green. Using the dots and their colors and how they are located will tell you whats wrong with your computer....BUT if its just shutting off then yeah sounds like a CPU problem.
When it would turn on and not display..would it turn on and then do absolutely nothing..no beeps no post..or would it beep and post and get to almost to windows and reboot? If it didn't post or no beeps or anything it is 100% your processor. I got lucky and after cleaning off the mess that guy had made, jumping the CMOS and removing the battery made it work again. Maybe you need to clear the CMOS and remove your battery and make sure you don't have any jumpers on the board set wrong.. if you do have that MSI KT6V board you don't have to worry about jumpers with FSB settings on the mobo, just clear the cmos with jumpers near battery and remove the battery...read on clearing the CMOS is you don't know how to do it. That'll get your BIOS to default settings and maybe your CPU will start back up.