Wireless network setup

Hi guys,
I am facing a problem with a home network setup. Situation is the following:


MAMA'S HOME (WIFI ROUTER) ------ 1km ----- MYHOME (GREGORIAN 27dbi+ 500mW USB NETWORK CARD)

The problem is the following: i can reach mama's router (a Fastweb Cisco proprietary one that cannot be substituted) via Alfa 500mw network card and a gregorian antenna; everything works, but actually i have to leave a notebook connected to the Alfa usb card and establish an ad-hoc connection to the notebook integrated minipci wifi card from my desktop computer.

This way so, from my desktop i connect via the adhoc network to the notebook and the notebook acts like a router, forwarding my packets thru the Alfa card and gregorian antenna to my mama's router.

What i wanted to do is to remove the notebook and add comething like a repeater. The problem is that most repeaters receive and re-trasmit signal on the same antenna, this way so, they are useless in thi setup as they would repeat the signal over the gregorian antenna. And most repeater's cards are low-power (a DWL-G710 I have does not find mama's network if connecter to the gregorian).

In there any reasonable solution? Any of you faced this problem? I own a Dlink DWL-G710 and a Linksys WRT54G (both useless? Usign WRT54 as a range extender in this setup with DD-WRT?). Does any of you know a high-power multiple-antenna wireless repeater?

Thanks for you help.