Our local cable TV company -- Bresnan -- has been running ads trying to convince people that Bresnan Internet is superior to DSL. They've been doing this by 'comparing' DSL speeds to those offered by Bresnan.
The ad consists of a person bringing up four different tasks, and showing the time it takes to accomplish them.
It's what Bresnan isn't saying in the ads that grates on me.
From the speeds they're showing, it looks like Bresnan is comparing their (theoretical) top speed of 8Mbps with DSLs (functional) minimum of 256K (if you're close enough, you can purchase higher speeds, too). What isn't mentioned is that cable's 8Mbps is shared (not necessarily equally) with ALL the people on a particular section of the line, and that DSL speeds are for EACH INDIVIDUAL USER. So if you get someone on a cable Internet line with the desire to use it, and hardware to support it, that one person may end up taking 6Mbps of bandwidth, leaving the rest to be shared by everyone else; if you get a DSL line, whatever bandwidth you're willing to pay for is all yours.
Another part of that shared line with cable is that if there's even one Internet Idiot that doesn't have his/her Windows computer up-to-date with antivirus, anti-spyware, firewall, and so on, that persons computer is going to be spewing out a lot of bullshit traffic: attempts to spread the Windows virus of the day, attempts to connect to any other unprotected Windows computers, sending out spam emails because the unprotected computer has been turned into a zombie, and so on. That will further reduce the amount of bandwidth available for 'real' Internetting. When I was stuck with Bresnan, I could watch as all the Windows machines on my section tried to get through my firewall - there wasn't a minute that went by that something wasn't happening.
Oh, and let's not forget to compare the reliability of the two services: how often does your phone go out, versus your cable TV/Internet? How long does it take each company to correct the problem, and does that repair 'stick'? As I'm typing this, Bresnan has had a problem with (at least) one of their 'gateways' (how multiple computers can access the same area -- much like the gateway in a fence): it wasn't accessible for nearly half a day, came back up for a couple of hours, and now appears to be offline again. Without that gateway, there could be several HUNDRED people without Internet access - even though their cable TV may still be working. This isn't the first time this problem has come up in the last few months, and isn't going to be the last: word I get from some Bresnan insiders is that they have way oversold their services, and don't have the hardware and infrastructure to support their customers as they should.
In contrast, I have DSL in my area precisely because Qwest has run fiber optic cables up here in the Heights: it literally runs under the street in front of my apartment building.
One last thing to consider is the level of technical support available. From my own personal experience, I have to say that Qwest is far, far superior to Bresnan. Back when I was stuck with Bresnan for my broadband, I was supposed to call their 800 number (a service center in Armpit, Iowa, I believe) to let them know I had a problem. The thing was, the tech support weenie I got was insistent that I go through their cookie-cutter troubleshooting sequence before conceding that there might actually be a problem with their hardware. What actually happened was that I eventually started calling the local office to see if they had received a report of an outage in my area.
The (very few!) times that I've had to call Qwest, though, I've been able to tell their service center people where and what the problem is: "It looks like I've got a problem with the nameserver at XXX.xxx.YYY.yyy because it isn't answering pings." "Hold on while I check it... yup, it's down. Okay, I'll get someone to reset it."
Problems with Bresnan generally took hours, if not days, to get corrected; Qwest usually had them straightened out in minutes (only rarely did something take an hour).
The bottom line here is that in realistic terms, if you have a choice between Qwest DSL and Bresnan cable, I'd STRONGLY recommend the DSL. In practical terms, you'll likely never notice any difference in the bandwidth 'differences', and the reliability and security of DSL is infinitely superior, in my opinion.