Thnx Shawn but the trick & catch is that i don't install it through or using any USB device every time that was only first time....

let say if something goes wrong & i can't get into my windows 7 through normal login, so i go to Safe Mode & see if i have "restore point" to fix the issue & if that's not possible (as it happened last week when i patched 3 system files through VistaGlazz & i couldn't got in & even restore didn't worked) so i went in C:\Windows7\setup & installed it completely again (only to screw it again in the near future bcz we are all born Geeks

,

) its working just fine....
What do you think about this method installing OS without any external hardware - No OS DVD, No Repair Disc, No external HDD, No USB device (flash drive/pen drive)....
People who don't know how to this i'll request don't try this till you are not confident because you might screw up few things..

..though its very simple & not a real rocket science, its just that i tried this but this might not work for you..

..So should be done under supervision & proper guidance...