Feeware CPU-Z is a program 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. What's New?

New CPU support : Pentium 4 HT, Celeron 2GHz.
New chipsets support : i845PE/GE, VIA KT400.
Sensor chip model (Mainboard tab).
New "ghost" mode (see "Parameters" below).
Fix SMBus bug.

Download CPU-Z v1.15 for Windows 95, 98, Me, NT4, 2000 and XP