Changing character set when the damage is done

Dear all,

I set up a DB with default values and it now uses the SQL_ASCII 
character set (as per "show client_encoding;").

I have copied in quite a lot of data from various Access databases but 
only now have I realized that all accented vowels show up differently 
from what I expected (I dare not cite some examples a they would 
doubtlessly show up wrong in the mail).

The contents are text written in Italian, so it's just the 5 vowels with 
an acute or grave accent. The user base is all Italian, so a quick and 
dirty trick is perfectly viable.

Any chance of running some smart UPDATE queries to put things right? Or 
elaborating on the fields whilst performing a SELECT query?

Thanks!

Alex.