CPU-Z is a freeware that provides some information on your CPU :

Processor name and vendor
Core stepping and process
Processor package
Processor current core voltage
Internal and external clocks, clock multiplier
Partial overclock detection
Processor features, including supported instructions sets.
L1 and L2 cache informations : location, size, speed, technology.
Motherboard informations : BIOS, chipset, memory, AGP. Whats new

Pentium 4 Northwood support
RDRAM timings for i850 chipset

Download Cpu-Z v1.11