Update your antivirus, temporarily disable your screen saver (choose None) and scan with your anti-virus set to scan All Files. Update and scan bi-monthly.
You can scan on-line to double-check your Windows scanner at
http://housecall.trendmicro.com/
*** Mandatory (get a firewall of any brand) - Get free Zone Alarm personal firewall anti-hacker countermeasure from
http://www.zonelabs.com. (not the ZA Pro demo) 'Don't let anything out to the Internet you don't know what it is.' Also please see
http://www.firewallguide.com/ for more information on why all on-line home computers should be firewall enabled.
***
Get, install, update and run free Ad-aware to find Spyware from
http://lavasoft.de/
***
Check your available resources by right-clicking My Computer; clicking Properties; Click the Performance tab. Resources available are displayed as percent there at top. Check it when you get done running the System Configuration Utility mentioned below.
Click the Start button; Run; type 'msconfig', without the quoatation marks, in the Run box and click OK; Then click the Startup tab; Uncheck anything you don't need running in the background. For reference on what's not needed running in the background in the System Configuration Utility, view this website first and print out the list:
http://www2.whidbey.net/djdenham/Running_items.htm
It's important that you print out the above mentioned list. The site provides a printer friendly link.