It's not you, it's more likely a combination of MacHTTP and WinMosaic. MacHTTP takes CR delimited text files and converts them to LF on the way out. The WinMosaic client probably expects CR or CR/LF for end of line and nukes the linefeeds. This causes the text to run together.
I believe the standard indicates that HTML files are supposed to have CR/LF line ends, but most Unix clients don't seem particularly happy with files in this format and like the LF only format better. WinMosaic should be more tolerant of LF only files and MacHTTP should probably send CR/LF line ends.