Old English is also known as Anglo-Saxon, the language in which many beautiful literary works were composed or recorded, such as Beowulf, the Law Codes of King Aethelbert of Kent, Genesis B, a particularly interesting form of Judith, the Wanderer, and many others.
Anglo-Saxon (which is a bit of a more correct term, since it was not limited to England as the name "Old English" might imply) of course being a branch of the Proto-Indo European language group (PIE, the best academic acronym there is), sharing roots with languages like Latin. This gives modern English a curious linguistic position as both a derivative and cognate language to Latin. A-S went out of fashion with the coming of the French-speaking Normans, but it made a lovely comeback, albeit in a significantly different form, when the Normans finally were well assimilated. At that point the language rapidly barrowed words from Latin so as to fulfill the role of intellectual discourse (of course, most intellectuals knowing Latin, a form of French, and English).
Thus modern English has the oddity of having Latin and Germanic-via-A-S words side by side (king and regicide, for example). It is neither a largely cognate language, such as German, nor a largely derivative language, such as French.
Anywho, I will endeavor to ensure that the next time I use the phrase "Old English" I keep in mind that I ought to assume an academic, rather than lay, audience, and thus be more careful with my terminology.