i got a cheap wireless g router i use it for my laptop and my xbox 360 which is connected directly with a cat5 cable will a faster router improve my speed even though im connected with the cables? will it make a difference
No I doubt you will notice any difference. Cabled connection is best and will provide you with the highest speeds.
If your experiencing "lag" in game its likely due to either your broadband speed, or the amount of bandwidth being used while your online. (If someone is downloading or streaming video/audio for example on your broadband, you will experience very high ingame lag due to the bandwidth used during download).