very very slow in loading anything

Why is my computer so slow?  Did speed test and it say 1.1mbps???  Is this because the computer is old and I have Windows 7?    Modem is in garage and Comcast has said numerous times they CANNOT move it inside.  We are paying so much money for this service and lately it is worse than ever.   I am not a technical wizard so I am looking for a pretty straightforward answer  in what I have to do to improve the speed!   Help!!