Vast difference in transfer speeds via network

I have set up a small media player, with connected external hdd (WDTVLive). I want to be able to transfer media files from my PC in an adjoining room over to the external storage drive attached to it. The WDTVLive can either do wireless N or ethernet cable. I have tried it both ways, and can see the drive & move files to it. I am connecting to it via a new Belkin N+ router (with gigabit ports) and a Dlink N usb dongle connected to the WD.
My issue is the vast difference in transfer speeds between the two. If I move a file from my PC over to the WD, the fastest speed is about 140 KB/s. However , if I move a file from the WD drive back to my PC, the speed jumps to 7 Mbits/s !!
Why is the transfer speed so radically different between them? I was on the phone for 2 hours yesterday w/ Belkin tech support & no answer was found. I turned off the the router's firewall, tried the transfer with my avast A/V shut off, etc etc, nothing will improve the transfer speed. I'm using XP Pro SP3.
I reconnected my old faithful US Robotics MAXg router this morning, & have the same issue , moving out to the WD drive = 140KB/s, the other way almost 7 Mbits/s. Can anyone advise what I can do before I pull out the few hairs I have left on my head?

What speeds to you get if you connect the drive directly to your computer via usb?
When you say "small media player". Is this another computer or what?

Also , I returned the Belkin router yesterday, and reconnected my trusty US Robotics MaxG router, and still see the same issue, media transfers faster in from the external drive/WDTVLive than the reverse. I checked in the System/Hardware under the network adapter in my PC for any settings that might help, but wasn't too sure what to look for. I also updated to the latest Realtek drivers, but nothing changed. Others have told me that they see pretty much equal speeds going to & from the same setup as I have , so it must be something in how my network is set up? WD includes a small app to map the external drive, which worked fine, I can see the drive under Windows Explorer. It is probably something simple, but for the life of me I cannot figure it out.

What is the nic speed on the WDTVlive? I didn't see it listed on the website.
Try hard setting the link speed to match what the router will do and hard set it also.

That's what I was wondering.

Have you contacted WD about this. Being that you have the same problem on multiple brand routers it could just be something with the WD unit.