I have both running on linux and windows and i never had to add any nodes.
Sounds to me like some firewall issue, have u checked that?
When u first run gexp in windows, the windows firewall will give a popup to allow connections to the wallet, make sure u allow it, else u cant sync your wallet.

Else u can see at the first page of exp how to add nodes : https://bitcointalk.org/index.php?topic=1173722.0