What resolution do you work in for pc only images?

I was recently working on some small images, 100x100pixels, and noticed that they set were to a resolution of 300dpi. That caused a big headache when it came to inserting text into the image as most of my fonts displayed to large at that resolution. The easy fix was changing the resolution but, it got me wondering.

Photoshop seems to think 72dpi is the way to go for pc based images but, a lot of the images i see are set at 96dpi or 100 dpi.

72dpi is fine for my sites