Assuming that you've run a virus scan with current definitions as well as a complete spyware scan and removal, the first thing to do is look at your system tray (the area where your system time is displayed). I've seen system trays with so many icons that it takes up 2/3 of the bottom of the screen--and that's just the programs which display icons to begin with--some don't! All of these programs are starting up when you boot up and can cause massive delays.

Identify which programs are firing up at start-up and either configure them to not run at start-up or delete them entirely if you no longer use them. Candidates to delete or configure not to run at start-up include any IM programs, Real Player, QT helper apps, media players, etc. Configuration settings will vary according to the program, so if you can't figure out how, visit the program's web site for information.

After that, go to your Control Panel and open the Administative Tools section. Open up "Event Viewer" and then click through the various event logs. Look for any warnings or indications of hanging programs or services and any other errors. If none are noted, move along. If you see any such warnings, check Microsoft Windows XP Support (http://support.microsoft.com/winxp) for further information.

The next thing to do is run a "registry cleaner." These programs will scan through your registry looking for leftover/bad/corrupt entries that can hinder your system's performance. I recommend Registry Mechanic (http://www.pctools.com/registry-mechanic/). It is inexpensive, easy to use and will find and repair most all registry problems. It will also compact your registry once it has fixed the problems it's found.

Next I'd defragment the hard drive. Turn off your internet connection, anti-virus and spyware tools (if running) as well as any other background applications showing in your system tray--then run defrag. These tips should get your system running like-new once again.