Linksys Wireless Router :: E2000 Very Slow - Need High Upload Speed

I bought an E2000 router as a replacement for my WRT54G router, since my internet speeds had been upgraded. But this E2000 router has been giving me nothing but trouble.
 
Wired through both the router or modem, I get my topspeed of 110mbps. However, as soon as I switch over to the wireless N function, my speed drops to only 25mbps. As far as I know, wireless N should have a much faster speed than that. Even my old WRT54G had faster speeds than this new router has. Mind you, that the distance between my laptop and router is about 3 inches away. The further I go away from my router, the speed exponentialy drops (20 feet, and the speed even drops to below 10mbps). Even with different laptops that have completely different wireless cards. Now honestly, I have tried EVERYTHING to get the speed up. Both 2.4 and 5ghz, 20mhz only, 40 mhz only, different channels (currently the router is in channel 11, being the only router in that channel), setting the network to G-only. I tried changing the Beacon interval thing in numerous settings, I even tried changing the MUT. Firmware is completely up to date. I have also tried placing the router on a completely different place, to make sure there was absolutely no interference (tough that shouldn't be an issue if my laptop is only 3 inches away) I tried changing the security mode to something different than WPA2/AES.
 
Nothing worked, if anything, it made it worse in some cases. I have litteraly tried every option I could find online, except for trying a third party firmware like DDWRT, which worked excellently for my old WRT54G, though I read that speeds can't be improved on this E2000 with a third party firmware.
 
Is there anything else I can do, or should I assume that my router is defective?
 
When I'm in my bedroom, I get a very poor connection and my speed drops to about 0.25mbps. Abysmal, so I bought a WiFi range extender to get me a better signal. It works, and it allows me to get a speed of about 5-6 mbps, without dropped connections. Still slow, but at least it works. The weird thing is, wired through my router or modem, I get  about 9mbps upload speed. With this extender, I get the same 9mbps upload speed in my bedroom, though only 5-6 mbps download speed. You'd think that the upload speed would drop simultaneously with the download speed. How can my upload speed be higher (maxing out) than my download speed? I wonder if my transmitting antenna of my router isn't defective.