[Mike]

As your house has too much concrete structure, you can try using Ethernet over Power adapters. You can also use powerful antennas. I do not think amplifiers can be of much helpful to you.

I do not what model of Linkys you are using. There are high output wireless routers that come with rf output and can produce better results. Try to use various wireless devices to connect the PC to the internet. Also use the combination of Ethernet connection and wireless access points.