The Argent Champion

To raise your Argent Dawn reputation in Cataclysm you need to complete the first part of the "Visitors" chain, up to the part where Fiona sends you back to Light's Hope for the quest Boys Will Be Boys.

After you complete the quest Argent Call: The Trial of the Crypt you will be offered two follow up quests, both are repeatable and both worth 2000 Argent Dawn rep each:
- Annals of the Silver Hand
- Aberrations of Bone

Simplest way to gain rep from there is to clear Strat Live (not so live anymore..?) and complete the Annals of Silver Hand quest 11 times. You don't even need to reset the instance each time, just run through the cleared instance 10 more times, fly back to LHC to turn in, and repeat. Using the LFD tool would be even better, if you can keep the completed instance open long enough.

This ^
Important things Iommie didn't mention is Argent Call: The Trial of the Crypt completion instantly grants you Revered with Argent Dawn plus more reputation based on your passive reputation gain (5%, 10% guild perks + human racial). Complete 9-11 repeatedable quests (also affected by reputation gain) = exalted. Also, the reason why you don't have to reset is the book is on a table, doesn't drop from a boss, but is unique.

Argent Dawn rep is a joke now.
From 0 to exalted, couldn't take you more than 3 hours tops.

Only for people who joined after TBC launch can Scholomance be confusing.

The Argent Crusade is not a section of the Argent Dawn sent out on an expedition to Northrend like the Cenarion Expedition was sent to Outland. The Argent Crusade is a select few from the Argent Dawn and the Knights of the Silver Hand, hand picked by Tirion Fordring, the Ashbringer. He selected the members himself to avoid spies, and agents of Arthas. As for the pattern... what? Yeah Naxxramas was Undead, but MC, AQ, ZG, and other pre-BCs weren't Undead... And everyone knows what expansions are coming, there's not much choice. The Emerald Dream, The Twisting Nether, The Maelstrom, The Nathr