I used to have Comcast when I was in Cambridge; that's why I switched to RCN when I moved to Somerville. RCN has a DVR option too, but it doesn't have as much capacity as a TiVo. Also, one day not long after I moved here I got a postcard from RCN, warning me that if I had one of their DVRs then all of my recorded shows would be erased on STATED_DATE. Which was two days before the postcard arrived.