I picked up the adventure Revenge of the Giants, and I think it would be great to run in the Eberron setting. Warning! There may be spoilers to the adventure.
Looking over the background and history of Argent, it looks like it's very easy to convert. I won't spill all the details/surprises of what I'm changing just in case any of my potential players come across this.
The first choice I made is the location of the city. I figured since the adventure involves giants, it should be set in Xen'drik. I don't have any specific place in mind, and the Traveler's Curse (Which changes locations/distances between places) is a good excuse.
The giant's goal and reason for the alliance is to release Piranoth. I'm still trying to decide who's really behind it all. At first, I thought the Lords of Dust could be behind it, but I don't want to over-use them. (They were part of a home brew campaign I'm planning.)
Another group would be one of the Cults of the Dragon Below, thinking they're releasing Khyber himself, not fully realizing what they're unleashing on the world. They could be manipulating the giants.
The third option is to let the giants themselves be behind it all. Some of the "smarter" ones (I.E. the titans) want to return to their former glory days.
There are also plenty of paralells in the adventure and the Eberron Setting. No heroes have shown up in Argent in 100 years. The Last War is the perfect reason for the lack of heroes from the Five Nations coming to Argent in the past 100 years.
The adventure also mentions the fall of a kingdom. Eberron has Galifar.
Rather than the Paragon Compact of the adventure, there is the Stormreach Compact Galifar negotiated with the Storm Lords. A slight modification/clause allowed Galifar to send heroes to Xen'drik sort of like an embasy. The Storm Lords realized they might need help if there was a serious threat, and it would be handy to have heroes in their back yard. (Or back pocket.) Galifar agreed Argent would not control or police the area. They were strictly reserved for handling world shaking events such as those that rocked Xen'drik thousands of years before. The teleportation circles allowed the heroes to return to Khorvaire when needed.
Boldrei is the best choice to replace Erathis. (Both have similar profiles.) Godess of civilization. Although, I think the whole Soveriegn Host should be represented. The Silver Flame would not have a presence in the city at the start of the adventure.