How can I tell that my machine is recognizing the new memory?

The easiest method is to watch the computer count up the memory when the machine is turned on. If you do not see the count, or you have a Mac, you can check it once the operating system is loaded. Mac users can check the "About This Macintosh" option under the Apple menu. Windows PC users can check their "System Properties" control panel (the last item listed on the right side of the "General" tab).