|I take it you are connecting via wireless.|
If so is the wireless interface adaptor you are using rated for 801.11n. If not you are no better of than you were with the 801.11g.
If it is actually the router that is disconnecting you while the router still remains connected to the Internet then it would seem like an incompatibility between the router and wireless interface card.
The 801.11n specification has only recently been ratified and any equipment made before then is likely to be incompatible.