Creating a Bootable USB Windows Vista Drive : To install Vista on to DVDLess Laptops
Format the USB stick as NTFS
Make USB Volume Active
Run
diskpart.exe and then set your drive and partition to point to the stick. Make sure you set the partition as Active.
Do this by:-
1. Run CMD
2. type diskpart
3. list volume
DISKPART> list volume
4> select USB drive
if the removable media volume no. is 4 , type :
DISKPART> Select volume 4
Create Boot Sector
There's a tool in Vista DVD called bootsect.exe. Its on the Vista DVD itself in the Boot directory.
Run bootsect /nt60 "USB drive letter"
E:\boot>bootsect /nt60 g:
Copy DVD files and Boot files
* Boot directory
* Sources directory and
* the files in the root directory
Finish.
Source :
here