Wi-Fi Problems

So right now I'm moving house, I'm moving right next door, and for the first 3 days that I slept in the new house, my wi-fi worked perfectly, the linksys modem is still in the other house while I was using it. I had full coverage on the Wi-Fi. Yesterday I get the Software Update alarm, so I just Update everything, and after that my Wi-Fi only gets one bar, and two if I get lucky in the new house.
Is anyone else having issues like these?
I know and have heard the Wi-Fi sucks on the Macbooks because of the case, but if I hard perfect Wi-Fi one day, then I update and it's gone, Is it a problem or a bug in the update?
Anyone else having this problem?

Macbook cases are plastic... so it shouldn't have any real effect... Are you talking macbook pro? Because even then, I haven't had a wifi issue, other than in my office which has a brick wall and two stud walls in the way. Where is your WAP in relation to your notebook?