Dell Studio M435 Vista OS

I purchased this pc a few months ago, Vista would never recognize my AirLink Wireless USB's, I purchased 3 different types and a Belkin USB.  Vista wouldn't recognize the drivers or report driver not signed even though the wireless USB's were Vista Signed...I have a sateliite system and work from home occasionally, my brand new pc is absolutely worthless, I just tried to Upgrade to Windows 7 because I had that option with purchase, but was told that ended on Jan. 31st...so what do I have to  to go by another computer just so I can work at home,  this is the last Dell product I will ever purchase...Amad, or whatever his name was couldn't understand me, I couldn't understand him and my customer care experience was a joke!  I guess I'll just load XP on it and not be able to access all the ram, or go buy Windows 7.