Switching to Mac OS X Tiger

Once you get connected to the internet with your new Mac,
make sure you click the blue Apple icon,
then select System Preferences ..., under sharing Pane
choose Firewall and then click Start to start firewall as below.



Next thing you must do, again click the blue Apple icon,
and then select Software Update ... !
It will automatically update all the softwares/drivers on your new Mac,
and save your time to call Support about known issues that have been
fixed already.

I find updated softwares usually run faster!