wireless speed problem

right, i've just moved my computer from downstairs to upstairs and i am now getting download speeds of under 1mb/s whereas when it was dirctly conected to the router i was getting speeds of 13 to 16mb/s. i have a DWL-G520M wireless 108G MIMO PCI Adaptor, and the signal strength is apparently very good. I dont believe it is the router that is the problem because when i run the speedtest on my laptop in the same position of my computer the speeds are around 11mb/s. is there anyway of improving the speed on my computer?

thanks