Without Your Own Computer -- Internet cafes are easy to find in Egypt around major tourist spots and in wealthy neighborhoods such as Heliopolis and Zamalek in Cairo.
With Your Own Computer -- Egypt uses 220 volts (240 volt appliances work as well) and standard RJ-11 telephone cables, same as those used in the United States. If you bring your own computer, you should be able to plug it in using an adapter, which attaches a two-pronged rounded (European) plug to your existing one. Most computers are able to automatically switch into the correct voltage, so that shouldn't be a problem. If you forget yours at home, most upscale supermarkets will sell you the plug adapter. There are also several Radioshacks in Cairo, as well as a number of local gadget stores that will sell you voltage converters.