I can only play the keyboard, and that very badly, but using the computer I manage to produce some tunes that some of my friends like.
One of my favorite quotes about making music is from Yamatsuka Eye of the Boredoms, saying "One of the most musical things I can do is listen." Which I feel is powerfully, deeply true. As gek said, every piece of art contains a huge number of decisions and listening and thinking actively about those decisions are some of the most musical things you can do.
Cornelius, it's interesting having you on this board because you constantly post broad statements which make me want to attack you, however, I agree basically with what you say here. Everyone can and should make music, it's really fun, feels great, is a better use of your time than playing video games or talking about it on the internet and barring things like tone-deafness (wonder how much this exists and how much is a suppressive myth) it's really not that hard, given a certain willingness to be bad when you start and a bit of time wading through that.
I wouldn't say that talent and genius are completely spurious though, I'd say they just make it easier for some to produce good work faster and with less fussing and deliberation. I'm thinking of one good friend of mine who is a visual artist and clearly has some kind of major talent, which is evidenced by the fact that he will make these insane, detailed, beautiful black and white drawings of complicated machines and perspectives and things and he just puts the pen down somewhere on the paper and starts this line which just continues and turns into the image. Basically, he's tracing a mental image onto the paper, there's no sketching, very little deliberation, he just draws what is there in his mind. That's what I call talent, the ability to do something good in a way that looks effortless, and I think it applies to music as well.