Need advice about upgrading Dell processor?

Unfortunately, any of the compatible processors are going to cost you more (part+ labor) than actually buying a new a new one. But if you know somebody who will do it for you extremely cheap, then you could go with this processor, which would give you the best bang for the buck.

Intel Pentium 4 Extreme Edition 3.4GHz 800MHz 2MB S478 They run about $250 and please dont buy a used processor unless you know who's selling it and how it was used, because as old as those are, used ones may not have much life left in them.

buy a new pc

this dell is only P4 cpu's thats all

if you cant afford much then buy another dell with an LGA775 socket

and that will support core 2 duo cpu's eg optiplex 745

they are all very cheap at the moment as they are business machines

and are being dumped by their thousands

its not worth spending any money on this one.

Only supported processors :

D7459 Prescott P4 Kit, 520, 2.8Ghz, 800FSB, 1MB

DD517 Prescott P4 64bit Kit, 521, 2.8Ghz, 800FSB, 1MB

D7460 Prescott P4 Kit, 530, 3.0Ghz, 800FSB, 1MB

DD519 Prescott P4 64bit Kit, 541, 3.2Ghz, 800FSB, 1MB

D7462 Prescott P4 Kit, 540, 3.2Ghz, 800FSB, 1MB

D7463 Prescott P4 Kit, 550, 3.4Ghz, 800FSB, 1MB

M8964 Prescott P4 Kit, 550, 3.4Ghz, 800FSB, 1MB

D7464 Prescott P4 Kit, 560, 3.6Ghz, 800FSB, 1MB

M8965 Prescott P4 Kit, 570, 3.8Ghz, 800FSB, 1MB

Honestly, you won't notice a performance gain from any of these options. Max out your memory if it isn't already.