Create a bootable USB pen drive from DVD (ISO) for W7

To install Windows 7 from pen drive instead of DVD.

The source DVD must be in ISO format.

To turn a CD, DVD, stick or file into ISO, download the UltraISO program. It's for a fee, but it gives you some free trial.

To create a bootable USB pen drive for Windows 7 from DVD:

you need to download this small program

Windows USB/DVD Download Tool