Even the manufacturer is hard-pressed to know exactly what upgrade limitations a given model will have. If the sales rep. Also, be aware when signing up for more than 1 or 2 years of Internet access that the quality from even the best companies can change, and 2 years is a lloonngg time in the Internet business. Some terminology Ports, Slots, and Buses are used to connect devices to the computer. Ports are for external devices that you simply plug in, slots are for internal devices on a card with their own special plug-in.
Buses are mostly hard-wired in place.
Bays are the physical spaces behind the front panel for holding storage devices such as hard drives, CD drives, etc. If you need the latest version of every program, software available only for Windows, or the security of a crowd, go with the dominant Windows operating system on an Intel-compatible computer. If you want a computer that works as advertised, is easy to maintain, and leaves your hair intact after installing new hardware or software, spend a little more and get an Apple Macintosh. Personally, we love them. But you will have to part company with the crowd.