If you managed to get this far, then congrats! You have successfully gotten through getting your hardware set up. if your splash screen shows up and it boots through then insert your OS cd to install your OS. If youíre using a USB drive wait until the splash screen loads and boot from your USB instead of your cd drive. If your USB drive does not show up then go into your BIOS and change your boot up option to your USB drive (remember to change it back to your hard drive after you install your OS!).
For those that want to install a windows OS from USB
(How To Boot And Install Windows 7 From USB Flash Drive (Updated)
If you are using an old hard drive, then uninstall your video card drivers, audio drivers, and network drivers on that old hard drive first. You can do so by going to Control Panel -> System - Device Manager.
If you did install a new OS, then install your new drivers from your motherboard CD. I highly recommend that you do not install video card drivers from the cd, go to the companies site (AMD/Nvidia) and download it. Once you get this all done, go download/do whatever you need now and you're all