I have windows xp pro. Even when I am not downloading, Google desktop constantly pops up with "computer has less than recommended memory (256 MB of ram). If you continue installing, your computer may experience poor performance. My hard drive is half full. This pop up slows down my system and I am always deleting.

Uninstall Google Desktop. If you still want it, reboot and reinstall it. Make sure you have the latest version.

If you have less than 512mb of RAM you will always get this error. Don't install anything but the basics on a machine with less than 1GB of RAM if you want it to function resonably quick. Google desktop requirements: http://desktop.google.com/support/bin/answer.py?hl=en&answer=10069