Help with Wi-Fi N router setup..

I have a D-Link DIR-625 wireless router.
It's B/G and N.

I have two laptops set up on it.My Dell D820 with a Intel Wi-Fi link 5300 A/B/G/N card.
And a Thinkpad T60P with Atheros A/B/G/N card.

I have the router set up with all defaults.I have WAP2 setup so i can get the N speed.
BUT the dell with the 5300 most times only connects at 60% to 80% single at 54 to 180mps.Most times at 54.

The Thinkpad with Atheros card shows the full 300 all the time but single at 20% to 30%.And it drops the internet all the time.

I could be 10 feet or 40 feet in the basement away from the router and it's the same on both laptops.

I'm not realy up on what setting work best for getting "N" speed's .

I know it's not the best router but i should be getting better speeds.

I'm looking for some guides now on the best way to set up the D-link router now...

 

just want to update...

I set the router to N only with WAP2 and if i get with in about 40~50 feet i Vista is showing full 300 speed.
If i move down one floor(about 60~70' away) it drops to about 130~180.
Then in the basement two full floors and on opposite side's of house , i get 54~80 and sometimes 130 in speed.

I dont know how trustworthy Vista is in the speeds but this is what it's saying.

 

Depending on what's in your floors, and what they're made of, that could be contributing to a significant drop in signal strength.