Conky it’s a known software in Linux environment for system monitoring which, for example, you can show cpu, ram, hdd, network usage etc… directly from desktop, moreover it’s highly customizable within skins and scripts.
Let’s see available alternatives in Windows environment:
Rainmeter (and the use of this skin) for 32 and 64 bit systems, supports skin and expandable with plugins
Wonky the “porting” of Conky in Windows, hosted in Google Code, still under heavy development, requires .NET, .xml configurations