Here's a small tutorial to make pendrives or USB drives bootable and to install Windows Vista using it. This trick come in handy if you don't have a DVD/CD drive.Installing from a pendrive will make Windows Vista installation very fast.
1. First you need to format the pendrive or USB drive in NTFS format.
2. This can be done by right clicking your pendrive icon and choosing format option.
3. Now from the start menu right click on command prompt and choose "Run as administrator".
4. Now type the following commands.
5. diskpart .The disk part program windows will open.
6. Then type list disk.This will show the list of disks in your computer.
7. Note down the disk number of your pendrive from the list eg. Disk 1.
8. Now type CLEAN.
9. Now type the following commands by pressing enter after each one.
10. SELECT PARTITION PRIMARY
11. SELECT PARTITION 1 (Assuming your pendrive/ USB drive is 1).
12. ACTIVE
13. FORMAT FS=NTFS
14. ASSIGN
15. EXIT(Now the disk partition program will exit). Now we need to give some more commands.
16. Now insert the Windows Vista Installation DVD and to your DVD drive.
17. Here i am assuming DVD drive as G and Pendrive as I.(Change it accordingly).
18. Now type G:CD BOOT
19. Type CD BOOT.
20. Now type this command BOOTSECT.EXE/NT60 I: to update your USB drive with bootmgr code.
21. Finally copy all the contents from the Windows Vista DVD to your Pendrive. Make sure you don't cause any errors.
22. Now set the boot priority to your pendrive from bios and you can proceed with the installation as normal.

Now vista can be installed on any pc with the help of this pen drive you have just created now.