Radeon HD 3850 512MB + X1950PRO 512MB in crossfire?

I currently have a DIAMOND Viper Radeon X1950PRO 512MB graphics card. http://www.newegg.com/Product/Product.aspx?Item=N82E168...

I am wondering if I purchased something like a DIAMOND Viper Radeon HD 3850 512MB, (http://www.newegg.com/Product/Product.aspx?Item=N82E168... )

if I could technically set them in an operating crossfire configuration at all, and if I can, would I want to? Would the old card drag down the new one or give a slight boost by having two cards working together?

I have a feeling that the the computer would not really appreciate the extra couple bucks of the old card as much as I'd like it to.

Also my motherboard is a DFI INFINITY 975X http://www.newegg.com/Product/Product.aspx?Item=N82E168... if anyone cares.

I've been wondering for a long time if directx10 compatible cards crossfired with only DX9 cards would get the DX10 features, but havent found an answer. Now after eventually looking into it more, my guess is it hasn't come up before because it doesn't make sense because the old cards probably just limit the new ones so everyone just replaces instead of thinking up crazy combos like this.