You really should brush up. DSL isn't set at a specific speed, there's 256k, 512k, 1024k, 2048k, etc in synch or asynch versions meaning upload will be the same or be different respectively. T1 isn't faster than cable unless the cable is less than 1.5mbps, course full T1's are a full non shared 1.5 synch. Fractional T1's are in 64k incriments usually with bursts of up to 1.5mbps. A T3 for DS3 (same basic thing) is 45mbps, usually only sold to larger business' and backhauls for ISP's. OC3's are 150mbps links again usually only sold to providers and large companies. There are many more speeds available, like the OC192 someone mentioned above, up to OC768 which is almost 40gbps only used for interstate backhauls through the likes of at&t, mci, etc.
DSL and Cable are simply a means to get to the ISP's backbones, whatever they may be; just like dial-up. I've had aDSL going over 8mbps for short runs, aDSL and sDSL can hit over 20 depending on the DSLAMs in use, vDSL will go much faster; around 200mbps. Cable can go well over any of those, but if the ISP doesn't have enough bandwidth to the net, you won't see it. I can provision my cable modems for various speeds from 256k to 8mbps (our current max speed that we sell) with uploads to 1mbps. Once my companies network goes to docsis 2 devices those speeds will be able to go even higher. Docsis 1 is capable of about 40mbps down and 10 up, docsis 2 ups the up to arond 30mbps max.
DSL is very dependant on the distance to the CO (central office) of the telco company, closer equals faster. Cable doesn't have this limitation as fiber is run from the HE to the nodes where it breaks out to the houses nearest the node. Usually very short runs so very little loss is incured. The cable network is basically just as capable as fiber systems as we do have the ability to run fiber to houses (or business') and run it straight into our backbones. Fiber will always have a max bandwidth advantage over coax however. Since we have fiber so fully deployed it won't be a huge step for cable operators to switch to fiber to the house through the use of multiplexing. I run point to point fiber for a few of my customers and I've turned up enough frame relay, T1's and DS3's to know what I'm talking about.
Please educate yourself on connection types and speeds before posting "DSL is 1.5mbps", it can only make you look stupid.