As far as I understand, Dlink is a quality company for network devices. Dlink, Linksys and - believe it or not - Microsoft are the best names in networking (for home use). But they are all so interchangeable that it's like buying one or another brand of toilet paper or bread.
Walls matter, but position matters too. Place it higher if you can. I had mine in the basement at the ceiling and it didn't work so well. Put it in the entertainment center and it was better but not great. Put it on top of the entertainment center and now it is perfect. The higher and more central location the better. Maybe if it's old, you could think about buying a new A/B router for like $20. Or you could add a second router, and put it in a different place. Tune the two to different channels. Then you would have great signal everywhere.
And if you ever have the option to run on an ethernet line - do it (like for a desktop computer or you sit at the same desk or couch on a laptop alot). Ethernet lines are at least 4 times faster than even 'G' wireless systems (some times much better than that), especially in real world effective speeds.
If all else fails, keep this in mind. Poor wireless reception is the worlds best firewall, because while you can barely use it in your own house, neighbors or e-theives would never be able to tap into your wireless signal from outside.