congrats on the new computer. maybe to offset the high price on the computer you need to sell your VM44 mics?
I think there are three options for this, imo.
1) buy a new router, specifically something with a long range like engenius brand.
my cursory search found this:
http://tinyurl.com/2colces and this
http://tinyurl.com/24poe66I don't know how far your cable modem is from an outside wall but I do know this same company also makes routers that can be installed outside.
both of these just happen to be indoor routers.
if you want to use DDWRT, go to
http://www.dd-wrt.com/site/support/router-database and see if any router you own is in their database.
2) run a cable. We all know cat 5 ethernet cable would give you faster speeds and probably the cheapest route because you don't need to buy anything but the cable. It would just suck if it got damaged because you have to replace it again.
3) bring the computer inside next to the other computer/router and connect it via ethernet cord.
let us know what you decide.