There is a one method though, that MIGHT prevent most spywares being installed on your system. Here's what you do:
For Win2k:
1>Start = Control Panel = Administrative Tools = Services
Scroll down until you see "Messenger", it says "Sends and receives messages transmitted by administrators or by the Alerter service." Stop the service by clicking "Stop", and disable it by using the pull-down menu and choose "Disable", then click on "Log On" tab, on the bottom white box doubleclick on "Profile 1" and it should change to "Disable".
2>Scroll down to TCP/IP NetBIOS. Now if you are running on a network and you often need to access other comps on it, then don't disable this, but do click "Stop", then from the pull-down menu choose "Manual", then click on "Log On" tab, on the bottom white box doubleclick on "Profile 1" and it should change to "Disable". Otherwise, stop it and disable it all the way.
3>If you are not sharing a network printer with other comps in the household nor do you need to access other comps, then disable "File and printer sharing for MicroSoft Networks".
4>Go to LAN setting properties, see if there's NWLink NetBIOS and NWLink IPX/SPX/NetBIOS compatible transport protocol. If you do, uncheck NWLink NetBIOS.
5>Click on "Internet Protocol(TCP/IP)", click on "Properties", click on "Advanced", click on the "WINS" tab. Now if you don't need to access other comps nor do you share printer, the click on "Disable NetBIOS over TCP/IP".
For WinXP:
Start=Control Panel=Performance=Administrative Tools=Services and go by the same steps as above. Then go to Internet Connection & LAN settings for the same procedures.
I'm a tech for a computer company and this is what I tell all my customers to do when they have spyware problems, and they are all happy with the end results. Hope these will also help you!