So my HDD is detected on bios.
It is on AHCI mode.
I ran the seagate tools (i have a seagate hdd)
it came back with 9 errors but the tool fixed it and it is passed now.
I use a usb stick Windows 7 Installer.
My laptop model is Acer Aspire 4750g. Cannot reinstall OS
BTW, I followed the instructions given there.
and i'm temporarily using a Linux Backtrack (it installed good).
Thanks for helping guys.