None . . .

Other than spending a full day in

• backing up all critical files
• reinstalling Windows and getting all the updates
• finding the proper drivers, downloading and installing them
• reinstalling all the programs that you need
• searching for the emails / dvd cases which had the serial keys for your programs
• copying back all the files into your machine
• getting all the settings and preferences to the way you like them

But end of the day, you will have a spiffy new installation which is a pleasure to use; and the back-up and copy-back process is also an opportunity to do some spring cleaning of the files dumped on your machine.

Apart from the time spent, you will end up using around 5 ~ 6 GB of data depending on what you need to download / update.

Sanjay