Humans are uncomfortable with change. It is often very difficult to get individuals to try new things. But, unfortunately, you don't have the luxury anymore of not upgrading your system. As you begin planning for an upgrade, get the word out asap. Have staff meetings, hold a brown bag lunch forum or if you don't have time to get together, send out a memorandum outlining the changes.
New computers are faster, but they are also more complicated.
It will take a while to get the bugs out as we begin using it on a daily basis. The next couple of months may be a little awkward as we make the transition from old to new, but it will be worth it. After you begin your training , you will probably find that simple tasks are harder to accomplish. It will take more time for you to figure it out. Please be patient - both with yourself and others.