Screws

The parts of my computer are held together with screws. Very tiny screws. Maybe a centimeter in size. Sometimes I have to take them apart. Usually for cleaning, as they attract crazy amounts of dust. Or, alternatively, to upgrade something. (New hard drive, more RAM, replace something that broke, new CPU, or whatever.)
I try to keep the screws organized. Mostly, because if I lose one, there is no hope of ever replacing it. Despite the standardization in screw sizes, they have no real names. "Screw with length of 1cm and hexigonal head and pitch size of 5mm." Well, more like "Case screw," "extension card screw," and "Fan attachment screw." The extension card screws are like a slightly smaller version of case screws. All of them use a philips head screwdriver, and the only way I have of getting new ones when I lose one is to order a new part, which will come with new screws for pretty much this reason.
I have a dismantled power supply, which I took apart to clean the dust out of it. It's from a dead computer. I can't put it back together, because I put the screws in my big screw case. I cannot find the big screw case. Accordingly, unless I somehow cough up eight "fan screws," and four "tiny screws," I can't fully put it back together. It sits, semi-dismantled, on my desk.
These screws cannot be terribly expensive, but without a name for them, I can't order more. Not without buying YET MORE PARTS.