Asus WiFi P5K-E-AP internet drops out

Hi,

I've recently moved houses into an apartment and now using the WiFi P5KE.
However, I'm having issues with the connectivity of it. I'm using it to connect to my brothers router in the other room. Signal is fine. And it does connect. However, it often disconnects. And I mean all the time. I will be lucky to be on the net for 30mins and then suddenly it drops out. Driving me insane.
Does anyone know how to solve this?
I originally uninstalled Wifi solo, but it still drops out.
I've also unchecked the option to turn it to sleep to save power.
Anyone know what I can do to stop it dropping out? (Especially when it eventually connects again, it always picks up the unsecure network in the building which isn't mine).

Any help would be greatly appreciated!!!

Ps. I'm running Vista.