Complicated Wifi Setup Help

I'm trying to setup a complicated wifi network with the gear I have at hand and am at my wits end. Any help or advise woiuld be great.

Here's what I have: Old isp router/modem, newer modem/router, usb wifi card with directional external antenna,and some computers, phones, and external harddrive

What I want to do: ISP modem/router works fine at my house. On the back of my farm I have a mother-in-law type place with no telephone service and some trees between us. the home router can't reach that far so here is what I did to get the signal. Directional antenna thru an old laptop bridged to and ethernet connection to the newer router.

I don't want to use ad-hoc because of security, shared external drive has personal info, and the phones don't seem to want to connect to it reliably. I know this can be done but I am way out of my league. I can pick up the signal at the in-law unit but once i bridge it stops working completly. I've spent more time on this then my wife will tolerate and I need admit it beat me.

Once I start looking at ip settings, dchp settings, dns settings, client settings I am just overwelmed. For instance I turned the DCHP off on the second router and now the ip of the bridging computer says autoconfig ip, strange ip, and won't let me log into the router anymore.

Please help,
Desperate

what operating system are you using on each machine?