I found on Windows 10 that the camera app send to do a good job of picking up my USB microscope. Much better than previous versions. Might not be relevant for you, but thought I'd mention it for others.
On Windows 8, the camera app is convinced that my microscope is a front facing camera, and so the image is mirrored, with no way I can find to convince it otherwise. My webcam, which *is* a front-facing camera by its nature, is of course not mirrored. Other than that, though, the camera app is snappy and works well.
The program I typically use is called EHE, and is provided by
Oasis Scientific for their cameras. It works with any generic camera, and is pretty barebones, but is fast enough that you can reasonably work under the camera--there's still a little bit of lag, but not enough to be a huge problem. I highly recommend it if you don't need anything fancy.