I wouldn't go with the Linksys BEF series routers/APs. I recommend the Linksys WRT54G or the WRT54GS. The reason I recommend these is because of the modded firmware available for the broadcom chips in them. There is a compay named Sveasoft that is creating great firmware called Satori. Their forums are here: Sveasoft
. The firmware gives you the ability to adjust the power going to the antennas from 24mw to 89mw if I remember correctly which will also extend the signal quite a bit.
Another thing I suggest is going to this site http://www.freeantennas.com/
and check out the parabolic reflector template antenna. I use 2 on my WRT54GS and it boosts my signal str by a lot. My neighbor 4 houses down can connect to my router which is much more than 100ft.
I hope that helps. Good luck.