Click this icon for the word processor, this one is the folder that contains all your work related documents. This icon is for web browsing, but stay off that unless you're on break. This is the menu icon down here in the lower left corner, just like you're used to, just look for the name of the program you need to run if it's not already on the desktop.
Click here, click there. It's all the same no mater what OS you're using. If it takes more than an hour to train the average employee how to to use a new OS with similar software, you need a new employee, that one's broken.
Now it may take a day or two to train the ones who create documents and a few days to a week to train those that write scripts/programs in it, but it is not going to cost more than the several hundred dollars (or Euros) it would cost for each user.