Some of this is going to sound stupid, but of course keep it in mind.
1) backup all your data ... pretty easy but most people forget the email program data ... for example if you're using Outlook it is best to export all your mail to a PST file. These can be huge so be ready to compress etc.
2) save any program settings you cannot live without ... example Office.
3) the best way to reinstall is to reformat the hard drive and start completely from scratch. DO NOT install over the original.
4) once you install, update the OS first before setting everything else up again ... connect to Microsoft and go for the updates immediately. Then go and update all hardware drivers etc.
5) start installing your software and getting back to normal (do it on a per demand basis and you will not have hours of computer set up).
And people wonder why I moved to Macs for my personal use.