If you do an Upgrade, all your applications should still be there and still work.
As always, do not bet the farm on that.
Have all your personal files backed up elsewhere, all your userIDs and passwords in a file or written down, and all of your application disks and installation files ready.
It usually works, but if it doesn't...it is far better to be prepared rather than to flail about trying to get things back.
And if you don't already have a backup situation in place, now might be a good time to start one.