I have watched many of these.... If you think you are remotely on the 'firing line' then I would take anything really personal with me today. You can always bring it back if you are lucky enough. The little stuff that doesn't matter they will box up nicely but still, take your important stuff today. You won't be going back to your desk or even saying farewell to people. While you are in the room all of your access is disabled and then you are given your package paperwork and asked if you have any questions. In that moment you probably won't have any as you are in an awful situation. However, don't sign anything! You can always bring in signed paperwork another day. Don't sign....
And btw.. if you haven't downloaded your contacts and emailed them to your home computer, you are crazy. Those contacts come in handy. They aren't company property so you aren't doing anything wrong. Just in case you might like having them.