migrating from MSSql

Hi there! I just started using postgres and I'm loving it. I really want
to go all open source at the office... I have a database in MSSQL which
I was able to export succesfully using the DTServices... But the client
application which contains a lot of SQL statements crashes every now and
then becouse of sql syntax...

Most of the problems I've benn able to fix, but there are a couple I
would like to ask about:

I have some querys that go like:

SELECT FirstName + ' ' + LastName AS [Customer Name] FROM tblCustomers

How should I write something that does the same (joins both fields with
a space in the middle and calls the resulting field 'Customer Name') in
a way that postgreSQL can understand?

Thanks to all in advance!