To unicode or not?

[aj]

SQL Server 2005 64-bit 9.00.3042 SP2

I am migrating a database to SQL Server that is not unicode...

Assuming that I have no plan to store different languages (other
than English), does it make sense to change my char() -nchar()
and my varchar() -nvarchar()?

My collation is sql_latin1_general_cp1_ci_as. Is there any relationship
between the collation and unicode support? I see that I can alter
existing columns, changing from char -nchar. So I could go unicode
later, yes? Is this a good idea?

If I go unicode, am I asking for trouble from other tools/protocols that
access the database, like JDBC/ODBC? If something knows about/supports
varchar(), will it also automatically know about/support nvarchar()?

Any thoughts appreciated.

aj