use the speedtest at
http://www.dslreports.com/tools its more accurate than most I've seen, plus it gives you a push/pull number. I'm usually more interested in the up because most broadband services offer at least close to a megabit down, but only a few actually give a decent up speed...
I've heard that cable is less secure than dsl, and I do remember hellacious amount of network scans, port sniffing yada yada...script kiddies trying out the latest releases on their own ip blocks etc.
I've had both and had similar results with both. I think an SDSL connection would be cool...I'm currently shopping for an ISP here in Sacramento, any locals got suggestions...?
edit:try out some of those tools on your connections and and post the results...I'd be interested to see which connections fair better as far as packet loss and what not goes...