If there's one thing that makes the blood boil around my place of work, it's having everything you need...but in the wrong file format. I get more irate calls about having a video that "worked fine on my Mac, but it's not working on this Windows machine" or someone fretting that "I have two hundred spreadsheets from Microsoft Works and Office 2007 can't open them."
Many complaints circle around the .docx format from Office 2007 not working in Office 2003, but that's surprisingly easy to handle. The real pain is distributing MOVs to Windows users who don't want to install Quicktime, or handling batches of antiquated data in abstruse file formats. (Ami Pro docs anyone? Works database files?)
I have two relatively cheap programs in my quiver that have proved invaluable.
For hard data files, Dataviz's Conversions Plus has been a staple of my software toolkit for more than a decade. It can translate all manner of obscure file formats into something you'll recognize, and power through gigabytes of old files in minutes. It's plain, it's simple, and it works. End of story. Except that it's about fifty bucks to license the download.
For video files, I have been using AVS Video Converter for about a month. MOVs, AVIs, MPEGs, WMVs...it handles them all. Of course, re-encoding video takes an age, and you need to know your output settings to prevent something you want on DVD coming out formatted for an iPhone, but AVS seems to have the task in hand. It's about sixty bucks to license the download.
My only gripe is that Dataviz's program doesn't yet have Office 2007 formats in its quiver. I hold out hopes...