input languages

hello

i have all my operating system (microsoft windows xp with service pack 2) in english, all software is also in english and i have "us" as the input language.
im portuguese so i need to write and work with é è â õ ç, etc...

im having two problems...

first is with the windows explorer, it makes a big mess with folders like
"blablábla"
it will create two folders that are named "blablabla" and "blablábla" if i remove one of them, the other is also removed.

the other one is with the software "mirc"
if i try to enter a channel named "blablábla" it will just enter "blabl" (it stops where the á is) i tried with /join and with the channel window, even if someone is in that channel and i make a /whois to right click the channel name and enter it wont!

do i have to do anything, i hate this problems, thanks!