In theory, a powerful computer and a good sound card (or two) is enough. And some good audio software. In practice, you need some more equipment, like a decent guitar, maybe a synthetizer (or at least a MIDI keyboard) and even a guitar effect/distortion pedal, like some nice digital products from Line6 or similar factories.
On the other hand, there are some interesting and feasable VST plugins that can be used for making the guitars distorted.
In the end, however, the most important thing in recording is having great songs. People are not going to listen your music if the sounds are not good enough, even if the production and the overall sound would be damn good. This applies not only to albums but to demos, too.
But... Making music should be fun, so take no pressure
.