Are you sure you can do that under the terms of the agreement? I have NEVER seen a high-speed IP give a deal without a penalty for quitting before you pay the regular rate for a period equivalent to the one you had the deal for.
Comcast has no contracts, so I don't he would have a problem with termination fees.
I've had Comcast cable internet for a few years. In my area there are very good introductory deals for DSL and for Comcast. So I told Comcast I was going to DSL unless they gave me "a taste" of what they are offering new cable internet customers. That their introductory offers are making me look like an idiot to stay with them.
I started internet cable with AT&T which gave me a modest introductory offer to start. Comcast bought them up and promptly jacked up prices. I never ever got any kind of deal from them.
When I go DSL I will buy my own modem on Ebay. Westell modems work on BellSouth's system.
Where I live mid range BellSouth DSL is cheaper than Comcast by 15-20 dollars per month. BellSouth was asleep for a long time but are now fighting back. They see that Comcast is a huge threat when they see Comcast offering telephone services too.
BellSouth has a marketing tie and package deal with one of the satellite TV services.
My library has high speed internet and the computers have CD burners. You can also plug in USB flash drives and hard drives
Theoretically I could go back to dial up (10$/month and less from WalMart and others) and do any large patches and downloads at the library and take them home on disk. And have people call me on my cell phone if they need me. Inconvenient but I could do it particularly on the short term.