So after much consideration I picked up a WNR3500L the other day to replace a D-Link POS wbr-1310.  Out of the box I was immediately satisfied with the router.  Easy to use, did what it was told.  Good stuff.  This is my first open source router and once I was satisifed with the stock firmware I put dd-wrt on it, with plans to go to Tomato shortly.  While the additional untilites and the such in DD-WRT are nice I saw no siginificant improvement in the connection.  With all that said here's my question. 

I've got a laptop with a 802.11a/b/g Draft n 2.0 Atheros AR5B91 connecting from about 10 feet away.  With both the stock and dd-wrt I can only get a connection of about 65 megabits per second.  I was kind of hoping for more, however this connection is certainly nice.  I've got the antenna power set to 71mw and the connection type set to Mixed.  I suspect that the limitation is on the laptop side and was considering getting a USB wireless adaptor to see if I got a better connection.  Before that I was hoping someone on here might have some ideas on bgetting a better wireless connection out of this thing.  I'm not expecting a 300 megabit connection, but I Would have certainly thought that I'd have managed more than 65 megabit.  Any ideas or suggestions?

Many thanks!