Desktop wireless adapter has poor reception

[Alanmelon]

One of the PCs in my house is having trouble picking up my wireless network. It's a desktop PC with a BT PCI Wireless Adapter.
Initially it was detecting the network ok albeit with a low signal strength. However, since upgrading the PC to a new motherboard/case etc it's been extra flaky and now fails to pick up the network at all.
It's all installed and functioning properly, and even picks up the neighbour's and the local free 'city' wi fi network. I initially thought it may be too far from the router and there are a few walls in the way, but then why do both laptops work when even further away (downstairs)? And why did it work ok in the old configuration PC?

An ideas on how to solve this would be much appreciated.

[Wicked_and_Crazy]

I've had these issues too with a Linksys card. I had the wireless card in a desktop PC that could hardly connect yet if i used a wireless laptop whilst sitting at the desktop the laptop had no connection issues at all.

[Graham M]

Is the Aerial stuck right down behind the computer and desk? This can cause issues