How many walls does the signal travel through?

Perhaps more importantly, what are the walls made of?

Are you using an extension ADSL cable from the router to the phone jack?

It could be a huge number of things, even after 50-60 feet, you should still be able to receive a decent signal, provided it's not travelling through four concrete walls.

My best advice would be to put the router in the laptopping area. If you have another PC it needs to be cat5/6'd to, it safe to run ethernet extension cable. It could also be your mum's wireless NIC.