|"i dont know much about computer upgrades"|
I posted the specs to your machine...did you look at them? The motherboard uses the "socket 7" not the "socket 478"...you can NOT install a socket 478 Pentium 4 Northwood CPU in a socket 7 motherboard!
You have an outdated system. It's 10 yrs old & not worth spending any money on. If it's running slow, it's because you're trying to run XP on it. The processor is way underpowered & you you probably don't have near enough memory. Go back to Windows 98 until you can afford a new system.