What regular things can you do to keep your PC running in new condition?
I recommend the following tips for regular maintenance:
Defragment your hard drive weekly
Use ScanDisk to search for and fix hard drive problems
Clean out your temporary files folder
Check the number of applications loading at startup, disable any unnecessary apps
Keep your computer fans clear of dust, hair and debris, make sure airflow is good so your hardware doesn't overheat causing errors
Run a weekly spyware scan to ensure you haven't picked anything up while surfing or downloading
Reboot at least once a week to clear any fragments of non-running programs
Turn on Windows Automatic Updates to ensure you have the latest performance patches and hardware driver updates
Clean your Internet Explorer cache and temp files
Ensure there are no large files stored on your Windows desktop, these can slow performance dramatically.