CDR vesus DVD-R : The Difference?

[savrip]

I just bought my new solderless modchip, and I'm all excited of course to backup my games. However, I'm reading on here that you can not backup your DVD-ROM PS2 games without getting rid of all the movies on the disc. That is of course what drives the story line and is one of the coolest things about PS2's.

However, how do you tell if a disc is a CDR compatible or a DVD-ROM? Glancing through Best Buy's website, it says everything is a DVD-ROM. If that is true, then what's the point of having a modchip (since I don't have a DVD recorder).

Also what is a good price for a DVD recorder? All I have seen is about $700-$600. That is way way outside my budget.

Can anyone help me out?