|"Just wondering if all 478 mainboards are compat with this cpu??"|
Since it's a 400MHz bus chip, all motherboards should work with it. Earlier boards (manufactured before 2002) may require a BIOS update to properly recognize a Northwood core CPU.
"I'd say the Celeron 2.30GHz/400FSB is roughly equivalent to a P4 1.6GHz/400FSB."
Depends on the application. The Celly-2300 would beat the P4-1600 in audio encoding tasks, since these applications rely primarly on clock speed.
Clock speed and cache are equally important for video editing/encoding/decoding, so the two processors would probably tie there.
In everything else (office apps, 3D rendering, gaming, internet browsing, virus scanning, file compression/decompression), the P4-1600 would outperform the Celly-2300. Cache really boosts the performance of these "branchy" applications.
Pentium M oc'ed to 2.82GHz, 667FSB, 2MB L2
3GB of DDR-800 @ 667MHz
Modified PowerMac G4 'Quicksilver' case
HDMI to homebuilt 1080p projector