What are some alternatives?
When comparing Core Temp and SpeedFan, you can also consider the following products
Open Hardware Monitor - Monitors temperature sensors, fan speeds, voltages, load and clock speeds, with optional graph.
iStat Menus - "An advanced Mac system monitor for your menubar."
CPU-Z - CPU-Z is a freeware that gathers information on some of the main devices of your system : Processor name and number, codename, process, package, cache levels.
Sidebar Diagnostics - SidebarDiagnostics - A simple sidebar for Windows desktop that displays hardware diagnostic information.
Real Temp - Real Temp is a temperature monitoring program designed for all Intel single Core, Dual Core, Quad...
HWMonitor - HWMonitor is a hardware monitoring program that reads PC systems main health sensors : voltages, temperatures, fans speed.