I don't know if you mean 1 megabit per second isnt so bad....but theres honestly really nothing to be done. Many companies can claim they can help with speed-up programs, download managers, etc.. but they cannot. Theres not much you can do to make anything any faster at all. If we could, why wouldn't we all have dial-up running at 1000mbps? Low cost-fast speed. Not happening.
You can check certain things to ensure theyre functioning properly but they probably are. You could find some tweaks..but they wont help.
One thing you might check is (and I know nothing about ADSL but I'm betting it uses the phone line too...) that you dont have too many phones plugged in, because they use bandwidth, and that they all have filters....