if you look they are the same linux client. as for the wine and windows verison just because it shows a higher iterations per second doesn't mean it is. If someone runs one for a week than the other for another week which one got the most dp's is the one I would assume to be faster.
As res0r9lm says, the ecompute.org page just points to FeLine's version.
I have a feeling the windows client probably is faster - likely the code was optimised for their compiler and not for gcc. Hopefully we'll be seeing optimised clients soon (and athlon optimised clients! pretty please?)
It's fairly easy to get the wine version working, but seeing as I can't get it to work without X, I reckon the native client will be better suited for cows (headless ones in particular...)