I have had the exact same drop out problems you've described (even within 1 metre of the wireless router). I have an MSI RG54GS wireless router with an INTEL PRO/WIRELESS LAN 2100 3B Mini PCI adapter. I tried updating all my drivers and it still wasn't fixed.
However, intel has published a list of known problems with the Mini PCI adapter on their website. One of the articles (
http://www.intel.com/support/wireles.../cs-006205.htm) described possible drop out problems due to router manufacturers not implementing PSP correctly. After following thier temporary workaround solution, my connection is back to normal.
Hope it helps all you poms.