I got my Back Track 4 R2 running on VirtualBox on my laptop (Fujitsu Siemens Amilo 2636 Si) I have 2 wireless network adapters: 1 built in and other one is USB (TRENDnet TEW-648UBM) wireless network adapter. I have installed drivers for TRENDnet adapter for Windows 7 and my Windows 7 detects wireless connections with both adapters. Back Track doesn't detect wireless connections with any of them. I heard somewhere that Back Track doesn't detect connections with built in adapter so I bought that USB adapter and Im afraid for no reason!
If need more information the ask me!!!