Do you have the ISO? Go grab a 4GB USB Flash Drive!
If you have problems with the DVD install try this:
You can download the USB tool for free and copy your Windows 7 ISO to the USB. Complete instructions can be found here:http://store.microsoft.com/Help/ISO-Tool
I use USB flash drives all the time for OS install it works perfectly - lot faster and no DVDs to get scratched and damaged! :-)
Microsoft Windows Client Team