The connection string is dependent on your driver and not on the database server. So if you are using the same driver, then you don't need to change anything. I'm not sure if there is an updated driver for 2005.
Is "SQL2005" the name of your instance? Do you have both 2000 and 2005 on the same server? I just installed the dev-edition last night on my laptop on which I have 2000 from before and I just named my new instance "SQL2" so I wondered if I had to use the same connstring as you.
-- Lumbago "Real programmers don't document, if it was hard to write it should be hard to understand"