Well, tri-spec hasn't been alive since... geez... beta? (Well, Ok, there is one experimental build that I've seen but it's not raid viable.) So you might consider doing some reading up here and EJ a bit more often =)
Deep Frost is based around Frost Strike (and Oblit) which is weapon-dependent and thus not ideal for DWing. DW Frost is based around RP generation and IT spamming with a lot of crit/haste. A pretty specific gear requirement, trust me. And it doesn't go for Howling.
Right now the only "kinda good" DW builds are, as mentioned above, Unholy. There's a really useful
thread on EJ about it if you're just dying to go for it and ever so love gearing Hit.
In the end analysis, so far, DWing is not putting out the same damage as 2-hand builds (even some weirdo experimental ones). Now, this is important: If you don't raid hard mode keepers in Ulduar or Sarth-3D it's not that big a deal. Have fun swinging your two swords/maces/fish/whatever. Just be aware that you're not going to do as much DPS as you could be. But if you are pushing progression, it ain't no min/max my friend.