I've had my computer for 3+ years and use it all the time for work. You can only do so much "cleaning up" before you find your computer full of "junk" so deeply embedded that you can't get it out. The only choice is to backup the important stuff to an external hard drive, format and reinstall. I decided to upgrade to Windows 7 because I heard that it is so much better than Vista. That install took forever. Absolutely forever. Not really the install itself, but the 50+ updates that needed to be downloaded and installed in a series of resets. I started this project in the morning at 9am thinking I would be done with the whole kaboodle by noon. Didn't get done until 9pm that NIGHT! Then, the next day I had to take the entire morning and reinstall/activate all the software programs I use on a daily basis. That sucked out that morning. Moral of the story....when upgrading your OS, do it on the weekend if at all possible.