Imac Wifi not so good

I have a iMac - I7 (1 year old)
I also have a MacBook Pro 15' (2 years old)

I share the wifi with my neighbor because he get's business internet and it's a lot faster.

I live above him and I can get his wireless internet without any issues on my MacBook Pro. However my Imac has a lot of trouble finding it. when it does find it drops the connection after 2 minutes, and it never remembers the saved information. it doesn't remember that I connected to this wifi before and doesn't remember the password.

2 questions.

1. Are Imac known to have such problem? or an inferior wifi range?
2. Is there anything that I can do too better the reception?

This is extremely frustrating as I can seat in front of my Imac with my macbook and get connected right away on my macbook, while my imac cannot even find it.

No known issues with the iMac. I have both an iMac and MacBook here at home and both get excellent reception. Of course it may be that I have my own router in close proximity. Whatever your reason is for sharing a connection, it's never a good idea regardless of how fast it might be. It's always a matter of distance and bandwidth.