Atikmdag.sys error won't start windows

I have had trouble updating an ati radeon hd4830 graphics card on my hp envy. When I updated I would get bsod on win7. I decided to upgrade to win8. The upgrade would fail with no error code. So I do a clean USB install of win8. It completes the install an I start setting up win8, once I finish and it tries to boot into windows it crashes and says error video tor failure (atikmdag.sys). Also the screen usually goes to a really low resolution so it's hard to read.
Any ideas what I can do?

I ha a huge problem with the same computer. I then stumbled onto this site. ALL these drivers worked for my windows 8 & Windows 7 install.

[Drivers] HP ENVY 15-1XXX (INTEL)

Ok thanks, so how can I update the driver if I can't log into windows? I'm basically stuck without an operating system now that I tried a clean install.