Reusing windows 7 oem on the same machine.

Why waste a $150 Win7 professional license by replacing it with another you bought when you only needed the disk provided in Clean Reinstall Windows 7 ? You should return the disk to Amazon if they'll take it, sell it or use it elsewhere.

Again, I would create the installation media from above tutorial for the licensed version which came with the PC by downloading Win7 Professinoal x64 English Official ISO Download then using the tool provided to burn to disk. If disk still won't boot write same ISO to stick. Make sure all USB settings are enabled in BIOS setup. Delete all partitions during the booted install.

You can indeed replace the HD within a year via WD Tech Support who may want you to confirm its condition using WD Data Lifeguard bootable flash stick and Windows version.

You are correct that the files were copied before install and apparently you moved the drive before the drivers were installed so it didn't require replacing them which could have fouled out the install.

This is only a workaround and as you say you still can't boot a disk so have no bootable repair tool until you can get the disk or another burned disk or flash stick to boot.

yeah, i didn't know where to get the os so i just bought it along with the code, and i don't have a flash stick lying around.

and also, i only did that when it restarted during the time it finished the "installing updates" part coz it tried to boot from cd again.

i just finished installed all the drivers needed.

btw, can i use my laptop's serial number coz it was originally professional edition on the w7 home edition installer?

No, you can't use Professional serial number which is worth $150 on a Home Premium install. So you should do it over. You used a workaround to install which is not enough since you need to have a bootable repair method, so you need to burn the Professional disk now to see if you can get it to boot. If so start over and do a Clean Reinstall Windows 7. If not try the flash stick method.

As a workaround if you absolutely cannot get the DVD to boot, then try burning a System Repair Disk so you have a bootable repair method. Then you can start the Win7 Professional installer from within Windows to overwrite C, making sure you choose the C partition to install upon. Only do this if you cannot get installation media to boot.

Are you following the steps in the tutorial, and if so why are you installing a bunch of drivers into a Driver-complete OS? This can cause problems right there. The steps for drivers are important enough they are printed in red in the tutorial. You should have installed only install Network LAN driver if necessary to get online to install all Important and Optional Windows Updates before checking which drivers were needed.