Rounding corners on Homepage Featured Content images

Hi, I'm wondering if there's a way of rounding the corners on the images that go with the homepage featured content? Even better, is there a way to set rounded corners to any images you use on the site? Also, if I add an image like here (http://gator3022.hostgator.com/~gmhrw/?page_id=12) is there a way of getting rid of the faint grey boundary line by default?