heya tooldawg;
There is actually 4 different versions of the p4 3.4Ghz.
The difference is the P4c is socket 478 w/ 512KB of cache, the P4EE is socket 478 with 2MB of L3 cache, the p4e is socket 478 with .09 micron process with SSE3, and 1MB of cache, the p4-550 is LGA 775 with .09 micron process, SSE3, and 1MB cache.
Thats about it.