App that facilitates viewing and editing .ppt/x files

I need an app that makes transfering, viewing, and editing Powerpoint files/slides on a iPad easy; from my Windows computer to iPad, and back.

The apps that I'm aware of, but not much familiar with, are - Keynote, Quick Office Pro, Documents 2 Go Premium, Office 2 HD, and Goodreader.

My prefered method for transfering the files back and forth is through iTunes' File Sharing; I'm not interested in using online-based/assisted apps, since I want to be able to view, edit, and save files on my iPad without an internet connection.

Do you know which of these apps (or of any others) makes this happen?

I'm not working with audio clips or videos on slides/presentiations so that's not an issue, but I do want to retain font formats and pictures (i've heard Keynote has trouble doing that). I also don't want to be converting files back to powerpoint format (.ppt/.pptx) when transfering them back to my computer (a la Keynote) in order to view them on PowerPoint again.

I use an old version of Powerpoint (2003 i believe), but most presentations I care to transfer and edit are from PP2007.

So, an app that can transfer to & back, view, and edit these files on my iPad without needing wi-fi. From my understanding, Documents 2 Go (Premium) looks the most promising here.

Anyone agree or have different suggestions?