Help finding cpu to buy

this might be a dumb question but i am trying to find a 1.4 Ghz or higher to work with my computer (socket 370) but am having a hard time finding one. how do you know if your computer has the cpu with tualatin or not. somebody told me it would not work if computer would not accept the tualatin cpu.
cpuid stated it is a intel pentium III EB 1000 MHz (socket 370 PC-PGA).
i would appreciate any help, i am getting sick of my computer being slow. i have done just about everything to it with (RUN) temp; regedit; antispyware; SDRAM; dont know what else to do but replace cpu.