I am trying to upgrade an old desktop with a ECS P4M800-M7 Motherboard (Socket 775) The processor is P4 2.8Ghz. The memory on the computer is 256MB and it is running extremely slow. I was wondering what replacement motherboards would fit and how easy/difficult is it to change out? (Socket 775?) and if I change it do I need to worry about my power supply, cooling fan? I have not done this before so I am also wondering am I getting in over my head? Thanks for the help?
Any mATX motherboard will fit. What's the purpose of the system and will you upgrade the motherboard, CPU and memory? Will you use the on-board GPU or a discrete video card? If you select a CPU that doesn't draw more power than your P4 2.8 and you use on-board video, then your PSU should be fine.
Edit: What OS and are you willing to reinstall it if need be? What other components will you reuse?