I suggest you to take into considerations the following links, they show the recommended settings in windows for best performance using the "N" protocol and some suggestinons regarding interference by other wireless devices:
What are the recommended settings for 802.11n connectivity?
Possible interference by other wireless devices may impact 802.11n performance
Data rate will not exceed 54 Mbps when WEP or TKIP encryption is configured
You can also try to update the firmware of the router.
I hope these recommendations help you with your issue.
I just got a new company notebook and hat exactly the same issues. My problem was that I used WPA with TKIP instead WPA2 with AES as mentioned here: