Who is "we" ExtraGonk? And why would you stop using VLC, its is a lot less 'messy' to play more exotic formats.
Anyway. VLC brings its own codecs and uses them. For Real and Quicktime you can download Real Alternative, and Quicktime Alternative which will include Media Player Classic.
What formats are you dealing with because you really shouldn't need a codec pack and sometimes those cause incompatibilities. If xvids won't play then I'd search out an xvid codec by itself, not part of a pack. So with Real Alternative, Quicktime Alternative, and xvid you should be able to play just about anything between VLC and WMP.