Most people do not need two video cards, especially someone starting out with PC gaming. Even as someone who is into PC gaming, I thought I might get two video cards, but never did. You have the option of buying a motherboard with an extra slot for a video card if you're building it yourself. If you're buying it, you should be able to find out if it can support two of them.
though as I recall you need 2 video cards to run 2 monitors and that's also something I'd be interested in because of music...
This is false. You only need one video card to run two monitors. I'm not sure, but some high-end video cards can support more (some AMD high-end video cards can do 6, IIRC). Generally though, you can expect any video card to support two monitors at least. There will usually be two or more connectors for it, and all you need to do is plug in your monitors, and set it up in Windows. It takes just a few minutes to do.
Note that not many games use dual monitors, although AMD (maybe NVidia now too?) has the ability to make most games run on both screens. Although, doing that on two monitors is not recommended (from what I gather from people who've used it, it seems like an odd number of monitors work best, either 3 or 5 for multiscreen gaming because of monitor bezels).
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Zachnorn
Everything = overrated.