<i>I'm going to pretend like I don't know you are trying to play burned games and point you to winISO</i> --PG

There are legitimate uses for this kind of question. For example to play my legally purchased Warcraft III in Linux, I need a no-CD crack because of the non-standard way WC3 checks for the CD. If I pay $60 for something, I think I have the right to circumvent the stupid copyright protections someone decided to put on the CD, if all I want to do is use my legal copy of the game myself in a legal way. Also, copying a CD to your HD can result in the game loading and running faster, because HD access is generally faster than CD access. I've found that no-CD cracks are the way to go rather than virtual CDs.

If you're using this kind of thing to play games you didn't pay for, on the other hand, you're just a bum.