I've compiled some addons I find useful for DK PvP. I've also included some mods you'll need for questing/instancing in Northrend. Every mod is configurable, and I've included align to assist you if you feel you need to rearrange the set-up at any time.
When you click download, click open. Click both the interface and the WTF folder, then hit "extract to" at the top. Select your WoW folder and extract them.
Once they are in the WoW Flder:
Go into the WTF folder and rename the account name file, the realm name, and your character name. They are renamed and tell you what capitalization to use.
After that you can close the folder.
Open up WoW, and click video/sound options. Set them the way you want them. My settings might not be right for your computer.
After that, log in and go the the character selection screen. Click addons at the bottom. Make sure you have load out of date selected.
Scroll over each mod and disable the ones you don't want. After that log into the game.
It will probably look a lot different than you're used to.
First off: Go to your interface/video/ sound & voice page and make all the setting changes you want to.
Once you're done with that I suggest logging out again and turning off anymore mods that you decided you don't want.
Under each mod you should be able to go to profiles and click Unholywraith if it doesn't preload my settings.
All of the mods a very configurable.
All of the mods tell you how to configure them on their own page. You can find the mods: