You can install windows 7 in many ways, one of them being creating a bootable USB key instead of using a DVD (cause lets face it installing from optical media is so last century and slow) . In order to do this you need the windows 7 install files (normally on your Windows 7 DVD or downloaded ISO file) and a windows vista/7 system to create the bootable USB key. a 4GB Usb key will do the job nicely here.
In order to create the key you will need to do the following:
Open an elevated dos prompt and type in “diskpart”
You will need to find the usb key by typing in “list disk” which will present all the disks available on your system (the usb key will have a smaller disk size so will be easy to spot.
Then type “select disk” and then the number that list disk gave representing the usb key. For example “select disk 1”
If the USB key is brand new you will need to create a partion on the key by typing “create partition primary” and then when it has created the partition type “format quick” which formats the partition as a fat32 drive using the quick method (perfectly adequate for what we want.
Once the format has completed type “active” which will mark the primary partition on the usb key as active and then type “exit” to get out of the disk partition tool.
All you need to do now is copy the entire contents of the windows 7 dvd to the USB key and insert the key into the target computer and configure the bios to boot from USB key.