Double Hop Point to Point Connection Advice needed

I want to hook to a Cable hi speed internet connection point 1, transmit
diagonally across a valley (2 miles) to point 2. there hook to a computer
and relay back across the valley to point 3. (1 mile)
Thinking of using a wrt54gl at the source, then 2 wrt54gl's at point 2 to
break out a connection, and resend.

Trying to keep the price down... Is this a good plan ? if so, how should
the wrt's be configured ?
Also do you think the 24 db grid antenna's at the below link are a good
choice ? Its the best price I can find (about $300 for 5 antennas. ) I will
need 4 antennas. This is in BC Canada.

http://cgi.ebay.ca/2-4-GHz-24-dBi-Re...QQcmdZViewItem