Sapphire HD 4850 w/ HDMI 512mb GDDR3 Driver help!

Okay, I am usually pretty good about figuring out my own solution to things but this has kicked me in the butt. I recently purchased a Gateway DX4200-09 product page: http://www.gateway.com/systems/product/529668220.php

I then decided to upgrade the power supply and graphics card to a Sapphire Radeon HD 4850 W/ HDMI 512 mb. The problem I am having is repeated blue screen errors, if I have the vista provided radeon 4800 series driver applied i get the memory management blue screen and if i have the vista provided hd 4850 driver applied i get the atikmdag.sys blue screen. Neither driver is what i want but apparently all i can download off of the sapphire website is catalyst control center which doesn't update any drivers whatsoever and if it installs drivers they are nowhere to be found.

Please help me all i want is my actual driver on my computer not the vista provided ones!