DSL line, Cat 5 cable??

After being tired of paying way too much for cable broadband, I'm switching to an ATT/Yahoo DSL line. I've never had anything other than cable, but I'm pretty sure DSL works the same way a cable connection does. The only question I have is, my kit came with a cord that looks like a regular telephone line, but is marked as 'Cat. 5 Patch Cable UTP'.

So is this cord I have and a phone cord the same thing? The main reason I need to know is that I need to get a much longer one to reach my desk from the phone jack. Which actually brings up another question: how long is too long when it comes to network cables?

Any help is appreciated, thanks!

Jam it back in, in the dark.

Thanks Render, packrat. I understand the regular cat 5 cable I've been using for years connects the modem to the router/computer, but I'm talking about the cable that connects from the phone jack to the modem. The cable I have labeled as "Cat. 5 Patch Cable UTP" is the same size and looks like a regular phone cord, not an RJ45(?) like the Cat 5 cable I've been using for my cable modem. All along I thought that DSL modems used regular phone cords, but this one threw me off.

There's nowhere I can't reach.