If you're not familiar with installing RAM yourself, you'd do well to make sure you have it added by the company you buy your computer from, if at all possible. When you do wish to upgrade your RAM, you'll need to know the specific type of RAM that it can use, as the specifications of RAM modules used have changed many times over the years. In addition, when opening any computer, one should be wearing a grounding device, such as a grounding wrist strap, available from Jameco

0-16MB
Grisly for modern apps. Fortunately, found only in older computers. 16MB would be okay for e-mail, and some Web browsing, but would be slow to impossible using modern versions of the popular operating systems.

32MB
Commonly considered the bare minimum for running a modern MacOS. It's passable for most modern apps, but not tremendous. It gives you some headroom, allowing you to run one large, demanding app, or several smaller apps at once (such as word processors, e-mail programs, Web browsers, etc.)

64MB
Generally, the default amount when buying a new computer, 64MB allows you to run some pretty heavy stuff, like Adobe Photoshop, as well as several apps at once.

128MB and above
Sweet! Run several large apps at once, switch between graphics software and movie software with ease.

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