Re: Wireless network range..
Not being able to use the net in the next room sounds BAD!
Mine works fine in all rooms. In fact, I've even used it in the basement once and it worked really well, alhamdulillah.
WEP reminds me how someone (must be in my neighbourhood) kept connecting to my wireless network for a number of days, so I ended up using WEP.
Btw.. you should call D-Link and ask them for help. If they can't help/fix it, then they should give you your money back.