German umlaut problems after moving from Windows to Linux

[Thomas Gehrlein]

Hi,

I moved my home directory from a Windows to a Linux box.  Now I'm getting
problems with umlauts in my .diary file.

I set the month name by loading german-holiday.el:

(setq calendar-month-name-array
      ["Januar" "Februar" "März" "April" "Mai" "Juni"
       "Juli" "August" "September" "Oktober" "November" "Dezember"])

C-x= on the "ä" in "März" says:

  character: ä (04344, 2276, 0x8e4)
    charset: latin-iso8859-1 (Right-Hand Part of Latin Alphabet 1 (ISO/IEC 
8859-1): ISO-IR-100)
 code point: 100
     syntax: word
   category: l:Latin  
buffer code: 0x81 0xE4
  file code: 0x81 0xE4 (encoded by coding system emacs-mule-dos)
       font: -Misc-Fixed-Medium-R-Normal--15-140-75-75-C-90-ISO8859-1

When I do C-u C-x C-e with point after calendar-month-name-array, I get:

["Januar" "Februar" "März" "April" "Mai" "Juni" "Juli" "August" "September"
"Oktober" "November" "Dezember"]

C-x= on the "ä" in "März" says:

  character: ä (07544, 3940, 0xf64)
    charset: latin-iso8859-15 (Right-Hand Part of Latin Alphabet 9 (ISO/IEC 
8859-15): ISO-IR-203)
 code point: 100
     syntax: word
   category: l:Latin  
buffer code: 0x8E 0xE4
  file code: 0x8E 0xE4 (encoded by coding system emacs-mule-dos)
       font: -Misc-Fixed-Medium-R-Normal--15-140-75-75-C-90-ISO8859-15

1) Which of the 2 "ä" is the "correct" one for a Linux system?
2) How can I turn all "ä"s in .diary in "correct" äs?
3) How can I tell Emacs: "Take all umlauts and other weird characters in my
   home directory and make with them whatever you want - but don't ever bother
   me with this kind of $&%$&$% again"?

TIA

Thomas

PS: The only German month with an umlaut starts next Monday.