TechRepublic has posted an article about how to install Windows Server 2008 on a computer that does not have a DVD drive.

There are two ways. The first one that they noted is that users can use the Windows Pre-Installation Environment boot environment. They mentioned that if a user is booting from a 32-bit environment such as the Windows PE disc, then he or she cannot launch a 64-bit version setup.

The second way is by redirecting a hardware to an image file. This method can be accomplished by using products such as the HP Integrated Lights-Out and Dell Remote Access Controller.

Source: TechRepublic