That looks correct to me. Maybe someone who is using ICQ on the N900 can confirm if those are the correct settings.

One thing you might try temporarily is to switch from port 5190 to 443 and at the same enable SSL.
Then there seems to be an alternative server login.oscar.aol.com, you can try that as well.
If that doesn't work, switch back.

Also, in this thread, it seems people have already experienced the same problem as you do, and discussed solutions. It doesn't really seem like they found an universal solution except using Pidgin.