Todays motherboards are ATX-form factor, I am not sure but somehow guessing that you have an AT-form factor. This means that you also have a different PSU (power supply unit).. .First step is to identify the CPU you want, than going from there to find a motherboard with the right socket and your required specs.. .Once you know the motherboard you can also decide about the RAM as there are also different versions on the market..... .If you really have not much experience, have a look as Jet II said, also search for ASUS-bare machines, they are just cabinets with motherboards and CPUs... <img border="0" title="" alt="[Cool]" src="cool.gif" />