go to desktop->My computer-(right click on)->manage->->Device manager-> now u see a window of Device manager
then go to Ports->Communication Port(double click on it and Open).
after open u can see a Communication Port properties.
go the Port Setting:----
and now increase ur "Bits per second" to 128000.
and "Flow control" change 2 Hardware.

U WILL NOTICE AN IMMEDIATE RESULT

this will increase the receiving capacity of your input port and thus ur netspeed will be increased