The spoolsv is the XP printer spool and is needed to run your printer. However, there is a darker side to this (and several other) XP program.
Several of the services in XP are designed to report user activy back to Microsoft. Microsoft describes 11 of them in this white paper "White Paper
One program that has a huge back door that most people have installed is Windows Media player. :Z Windows Media Player in XP, reports to a Microsoft server every DVD movie you play, including its title and a string that uniquely identifies your player
Not all of these programs report constantly, but periodically they attempt to send your history to Microsoft.
Brian Livingstone wrote about these programs that “report to the mothership” in his article “Putting XP in the zone”. He stated that the firewall in XP will not stop these programs because they are part of XP and therefore allowed by the XP firewall.
A lot of this was done with XP service pack 1. See the following article on the Sneaky Service Pack
Now just becasue a service is needed does not mean you cannot stop it from silently reporting back to Mircosoft.
Black Viper deal with a lot of these services and if they are required at his web site www.blackviper.com
Or tell your firewall not to let the program out. If it turns out later you need one of the services to access the internet, turn it back on.: