Your question and table makes no sense. Are you saying that you get more bandwidth when you transfer a file via a wired connection and less bandwidth when you transfer via a wireless connection?
PC1 -------wired-------- PC2
6MB/s or 48Mbps
PC1 ((( Wireless ))) PC2
1MB/s or 8Mbps
If so, 48Mbps on a 10/100 link is very respectable for TCP and 8Mbps is very respectable on a mixed-mode 802.11bg wireless network.
As you can see, these are all educated guesses because you did not provide any information. Your table makes no sense, please consider revising. Why are the Arrows pointed in both directions. Please provide the make and model of your router. Please provide the direction of your traffic. Please provide the size of the file you are transferring and mechanism you are using to transfer that file. I'm guessing it's Windows Copy, but you've got to clarify that.