Bleh confused.
The best signal and speed I can get is 20Mbps by only using the old router...
Also, lots of wireless traffic where I live. Not sure how some of them work at -10 decibels when I only get -30 @ 1ft
I get -55 at about 15ft (through a stud wall.)
It could be a directional antenna that you're picking up at -10.
You should be aware that you won't get the full 54Mbps if encryption is turned, I'm not sure what the exact overhead is. Also, the router <-> router communications will cut into the available bandwidth as well.
How old is the ~5Mbps laptop? It might be an older wifi driver / chipset. I'm clutching at straws here really, but it couldn't hurt to try to find an updated driver for it.
It might also be worth looking into replacing the wifi kit with something that is N rated. Seeing as you've got a ridiculously fast connection you would probably see the benefit. With that said, I suppose that depends on why it is you want a faster connection to the laptop(s) and if you're willing to spend the money.
Also, you could try moving the routers slightly closer together, as if they're on the edge of each others range you'll be getting slower speeds when you're connected to the 2nd router, despite showing an "excellent" connection on your wireless card.
It might be worth testing the wifi on the ~5mbps laptop on the 2nd router and then on the 1st router to see if it's the laptop or the router it's connecting to. In theory it should be connecting to the strongest router it can find, but it might not be. You can test this by creating a MAC address filter to prevent the laptop from connecting to one of the routers at a time. If it is getting the same speed on both, then the problem points to the laptop, if not, it could point to the router(s) and possibly the placement / distance / obstacles in the way.