I can add and extend this list a bit, this is the list of Dell validated CPUs:
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
This is about it. Numbers on the left are Dell part numbers from some time ago.