Game-Teched

Ok, at the moment the Frost Dual Wield spec for death knights is the most OP of the three main dps specs for death knights (while others may argue that unholy is better, I find that frost is a much more versatile spec). There are alot of different talent builds out there for this spec, and it depends on your gear, your level and how good you are. I would recommend a mixture of blood/frost if you are undergeared or aren't quite level 80 yet, because the boost from some of the talents in early blood can be a nice boost to your dps. However, once you get some decent gear or once you're 80, I would suggest moving all of these into frost/unholy. The auto-attack bonus damage you get from Blood-Caked Blade and Necrosis is a definate advantage to the blood mainly because the majority of your damage you will push will be from your auto attacks and from your frost strikes and maybe your obliterate if they crit enough. (keep in mind <--- all that is relating to single target dps since obviously your main damage generating attack during AoE situations will be howling blast and frost strike)

This is my current build, nothing to out of the ordinary here, oh and don't forget the glyphs, they're extremely important, at the moment i'm using Glyphs of: Frost Strike, Disease, and Obliterate and Minor glyphs of: Horn of Winter, Blood Tap, and Pestilence (this last one can be replaced by the ghoul minor glyph if you don't want to take up an inventory spot for corpse dust.
http://www.wowhead.com/talent#jZG0jxAMczf0cuzAofM0hxc:pkaM0m all that information can be found here, next I will discuss hit cap, expertise cap, and how to properly gem once you get there, as well as the "proper" rotation for frost dw dps.