Its really difficult to find guys like u who dare to do these types of things and 1 thing u must know that ure at right person coz i have booted Windows 7 , windows Vista , Windows xp ....... all of 'em from My pendrive........... PLEASE vote as Best aswer Dont 4 get dear first of all if u want to avoid all these tricks then goto internet and download CDBurnerXP and burn your dvd/cd image.. boot it be happy. But if u have courage and faith take your pendrive it must be atleast 4 Gb if u have Windows 7 / Windows vista iso image of around 2.33 - 3.5 Gb if it is of more than that use 8 Gb pendrive( i will use PD instead of pendrive) for windows xp u may use 1Gb PD. Switch on your system insert your PD . follow these steps READ CAREFULLY PLEASE >for win7 or vista open start menu type cmd right click run as Administrator.for xp just start cmd 1>type diskpart hit enter (ent) 2>list disk 3>select disk 0/1/2/3 or which ever is of the dim as shown same of ur PD but basically it is select disk 1 4>clean 5>create partition primary 6>select partition 1 or the no of partition selected in step 3 7> active 8>FORMAT FS=NTFS QUICK 9>ASSIGN 10>EXIT 11>minimize cmd do not close mount the image using " daemon tool " check the drive label on which it is mounted D: or E or F whatever it is here i assume it to be E 12>come to cmd and type the following command 13>E:CD BOOT or move into the folder containing bootsect.exe file 14>CD BOOT or till you are inside folder that i m talking abt it will look ilke E:\boot> 15>BOOTSECT.EXE/NT60 F: here F: is the letter of our PD 16>Exit command prompt closes now your PD is bootable and yre almost done !!!!!!!! copy all the files in the E: drive all means all everything which is inside iso must be copied ................... DONE restart your system keep on pressing F8 then u will see the boot menu select your pendrive and hit enter u will boot OR do not restart your system just go into the PD start the setup and rest will be done automatic.