Spyware or Adware?
Adware is any software application software which makes banners appear the whole time it is in function. Also, the adware program can install components that will transmit information about the user and its behavior and this work on his PC. Unlike spyware programs, the user is asked when the program is being installed. Actually, an adware application is the application that, along with its basic functionality, has a different one, the one that makes it show commercials once in a while, downloaded periodically from certain internet servers.
Spyware is a program, usually downloaded from the internet, which sends information about the user without him knowing it, every time he connects to the internet. Usually, the packages sent contain marketing information and not confidential information, although some programs can do that too. Go here for the latest info on XP Antispyware