The rise of cheap and ultra portable computers coupled with the fact that solid state storage - such as memory cards and USB drive - has become faster and cheaper than ever before means that it is now entirely possible to install Windows 7 on a laptop or a desktop using nothing more than a microSD card the size of a thumbnail.
There are a few things to consider beforehand though. Installing Windows 7 on any machine implies that there must at least be one USB port free and that the PC's BIOS will support booting from a USB drive.
Now a card reader is not the same thing since, more often that not, its proper functioning depends on drivers that have to be installed AFTER the OS, which kind of defeats the purpose.
Secondly, creating a bootable storage device means that the operating system will need to be installed elsewhere, most probably on the machine's hard disk drive, just as you would have done with an optical media (like an installation DVD).
If you have the Windows 7 ISO Image at hand, just copy its content to a flash drive with at least 4GB capacity. Alternatively, get an EXTERNAL card reader and plug in a microSD card or any other compatible memory cards.
This short tutorial will not only show you how to install Windows 7 from your USB drive but also how to choose the best USB drive for the job; handy if you are a system administrator.
Assuming you have administrator rights (if you are not sure, it is advisable that you don't perform this operation), press on Ctrl + R, Type "CMD" and press on enter. This will bring up the "command prompt" window. Put your CLEAN USB drive in the computer's USB port and your Windows 7 DVD into the optical disk drive.
Type DISKPART, Hit Enter and then LIST DISK command which will present you with all the physical storage device on your computer, including the Disk number of the target flash drive.
Again, assuming that the disk number of your flash drive is 1. Type the following commands (in capital letters) and press the "enter" key or [e]. SELECT DISK 1 [e] CLEAN [e] CREATE PARTITION PRIMARY [e] SELECT PARTITION 1 [e] ACTIVE [e] FORMAT FS=NTFS [e] ASSIGN [e] EXIT
For the sake of this tutorial, the DVD drive will be assigned the letter D and the USB Flash Drive, Letter F. Return to the Command Prompt window, type D:CD BOOT and press enter. Then CD BOOT and press enter again and finally BOOTSECT.EXE/NT60 F:
The above sequences will convert the USB drive into a fully functional bootable USB drive. After the procedure, transfer your Windows 7 DVD content to the USB Flash drive. Note that you should be able to use the drive to store other files after the partition has been created.