Your best bet is to take your tower to a local computer shop and let them see if it can be upgraded. You are probably faced with purchasing a new case w/power supply. Either the Intel P4 or AMD Athlon processors require an approved power supply that can supply enough constant voltage to meet the power demands of those processors. You could still use your drives, but would also need to buy a mainboard. processor, fan and memory. You are looking at $300 to $400 depending on what you get.