Now, the closest living relative of English is Frisian, but it has undergone a number of changes, some making it similar to English, some making it different. Icelandic is pretty close to what the Anglo-Saxons were speaking 1000 years ago.
Here's a video of a guy using Old English to try and communicate with a Frisian.
http://www.youtube.com/watch?v=OeC1yAaWG34Especially the part where the farmer says, "You want to milk her...You want the brown cow in England to milk." Though I think he might actually be trying to speak English there.