One thing I have noticed, if you carefully read the terms, most ISP's include the following clause: "Speeds up to_____". I've seen it on several ISP's contracts and usually there's an asterisk next to it, with a explanation at the bottom of the page saying speeds may vary due to numerous conditions & they do not guarantee full promised speeds all the time.
But yeah, it does seem a bit slow. Try hopping on late some night/very early morning and see if the speeds increase. If they don't, it might be worth a call to tech support.