If you’re running Windows, you’re probably running somewhere between 5-25 services that you don’t need, shouldn’t want, and ought not to expose to the network, especially if you’re on the public net (e.g., your laptop on a coffee-shop wireless hotspot).

http://www.securityfocus.com/infocus/1581

and

http://www.blackviper.com/WinXP/strangeservice.htm

are good resources to get you started there.