You may not get any more.
The type of router will affect the range, so if it is normal, wireless+, range max etc the range will be higher. The broadcast type, B, G, N etc is the speed. Nis much faster than G, G is much faster than B. You may see a range increase but it may not be that much.
The quality of adapter may affect it though. If you are using the standard one that came with the system then it may be integrated and crap. You can get a wireless rangemax adapter and it will pick up the signal alot beteter