I was tired of burning perfectly good DVDs repeatedly for Windows 7 beta testing. Instead, I decided to follow these excellent instructions and copy the contents of the ISO image onto a USB stick and boot from that.
My Biostar TF8200 A2+ motherboard has an American Megatrends BIOS. Configuring it to boot from a thumb drive is a bit tricky. Here are the steps:
Insert the USB thumb drive.
Enter BIOS setup.
Go to Advanced, then USB Configuration, then USB Mass Storage Device Configuration, then select CDROM for Emulation Type.
Press F10 to save BIOS changes and reboot. You must reboot for the BIOS to view the thumb drive as a CD-ROM drive.
Enter BIOS Setup.
Go to Boot, then CD/DVD Drives. Select "USB: USB DISK 2.0" as your 1st CD drive (assuming you have a real CD/DVD-ROM drive).
Go back to Boot Settings Configuration, go to Boot Device Priority, and select USB: USB DISK 2.0 as the 1st boot device.
Save BIOS changes and reboot.
When prompted, press any key to boot from the "CD-ROM" (really the USB stick).
In the end, I wasn't able to get the system to boot from the USB drive as a virtual CD-ROM drive. It would only boot from the USB drive if I changed the emulation to "Hard disk".