The P4 has a different HSF then the AMD sockets or the P3. When pruchasing, look for one that fits a p4.
Celeron 633 @ 1064 , Windows XP server,
Pentium 3 1000 @ 1100,Abit bx-133, 256 Mb Mushkin Rev.3 cas 2-2-2, ATI Radeon
AMD Thunderbird 1.4 @ 1.63 (24/7) IWILL KK266R , Corsairs pc 150 cl2, Leadtek GeForce 3 