The Best and Fastest Method For Rounded Corner Designs

This may seem VERY trivial, but WHAT method to use to create rounded corners, whether it be JS, PURE CSS, CSS with images, or what is something people talk about a lot. Cross browser compatibility and what not is always an issue to talk about. What's faster, easier, whatever. I'm doing some research. I haven't made my decision yet.

I want to be able to use a background gradient for a couple tables or divs(depending on what method i use)

I've seen Spiffy corners, but am not sure if you can use background gradient images with it and it seems very limited as far as the radius goes(unless I'm missing something. If someone could show me an example of using Spiffy corners for a rounded corner radius of 15px it'd be greatly appreciated)

I think if I was able to use spiffy and increase the radius by 15px rounded and use background gradients I'd be content.