Online Videos Playback / Animations Choppy With Full Internet Connection

I'm working on an Hp pavilion elite 210y pc. It's got a lot of stuff like amd phenom II 945 quad core processor. I have windows 7 and internet explorer eight and an at&t modem hooked up directly to the computer, the status bar says it has full internet connection and the specs of that look fine but the internet is kind of slow, not my biggest concern. My main problem is that it won't play videos without making it choppy and hard to see even after a video is loaded completely it still lags and won't play correctly. Pretty much anything that is animated and over the internet is garbage; internet games, ads, even text comes up slow.