Death Knight TankFollow

First, ALL TANK BUILDS SHOULD GO 5/5/5
sorry for the caps but you NEED that.

2nd, if there's no warrior make sure you get improved icy touch.
3rd, hungering cold = bad for tanking, 5/5 tundra stalker = good. HC is more of a pvp ability and has such limited use i dont see it being worth getting in pve.

4th get epidemic from unholy if you can, it helps a lot. since you are levelling this can wait a bit, i personally couldnt play w/out it though.
5: bladed armor from blood, if you have points for it, is also a significant dps boost.

6: frost aura doesnt stack with most resistances (fire resist aura, resist totems, druid resist buffs, etc). in raids i wouldnt pick it up. for solo levelling and instances (5mans) its not too great. its more of something you get in heroics i think.
7: acclimation does stack, but unless the mob has a damaging aura like sapphiron or loken its not really worth it (in my opinion) but it might be, thats really dependent on what you are fighting. for levelling i dont think its worth it.

You can keep icy talons if you want, it doesnt stack with windfury totem, but its pretty good to have soloing and dps in 5mans. killing machine is pretty nice but its hard to get that and icy talons with tank talents, plus it doesnt scale very well with tank gear because of low crit rates (so i usually only get it in dps or tank builds where we have a shammy droping WF). if you have a dps build and you want high soloing damage/burst i would pick it up.

For a levelling build i would do something a little more like this
http://www.wowhead.com/?talent=j0E0mZGxxthcdohoVosx0g

dont need to get epidemic right away. for right now drop acclimation and frost aura to pick up blade barrier and start working on tundra stalker. when tundra stalker is maxed get bladed armor, then get 2/2 epidemic and 4/5 dark conviction.

iv made a new build and i think its prety good http://www.wowhead.com/?talent=j0eMZGxxthcd0hRVssx0g