You can check your ethernet card by going to Device Manager. Click Start and right-click Computer, then click Properties. From there, click Device manager. Look where it says "Network adapters". If there's an exclamation or question mark there, you have an ethernet problem; if not you're OK. You didn't say whether you're using a wireless or wired connection. If wireless, I'd suspect the router or your ISP. If wired, I'd definitely suspect the ISP. Be aware that streaming video takes a right fast connection. If you have a minimal DSL connection, pauses (hickups) are to be expected.
I hope this helps. Good luck.