If you are running 7 Mbs you are not using T1 --- a T1 line has 24 channels capable of a max speed of 64Kbs per channel so a max speed of 24 x 64Kb = 1536Kbs or approx 1.5Mbs. Which at the time it was widely used was faster than the available alternatives but is nowadays pretty much lower end. The main advantage to a T1 line is that Unlike DSL or cable internet, T1 channels cannot be shared or piggybacked by another customer. Speed can never be degraded by another customer's usage.
But you are correct that nowadays Cable and many DSL connections are now faster than a T1 line due to improvements in the standards used for DSL and Cable transmission.
Also be sure to check your Cable speed over a long download period -- Many Cable services offer methods of increasing the speed for the first 30 - 60 Seconds of a download so that speed tests report much higher speeds than the line actually gets ! For Example on Time Warner they offer PowerBoost which they describe as :
So it is mainly a method of getting reporting software to show a faster connection speed than the actual speed of the service by letting you use a portion of others connections if they are not being used for the start of a download making users feel they are getting better speed than what they are paying for !