I have a Belkin wireless n modem router.

1 Macbook with Snow leopard
1 Windows 7 Notebook
1 Windows Vista Notebook 

Both the Windows notebooks have full strength signal, the macbook shows 2 of four bars (all 3 are 4 meters from the modem)

The Macbook is picking up neighbours wireless stronger than mine.

My Modem router is a Belkin  F6D4630-4 V2

Macbook is Wireless N
Notebooks are G

Any ideas