are you running windows 7 64bit ultimate if so your going to have problems as dell only supports 32bit windows 7 if your running 32bit windows 7 then look here
http://support.euro.dell.com/support/downloads/driverslist.aspx?os=W732&catid=5&dateid=-1&impid=-1&osl=EN&typeid=-1&formatid=-1&servicetag=&SystemID=VOS_N_1015&hidos=W732&hidlang=en&TabIndex=&scanSupported=True&scanConsent=Falseas you may have the wrong driver as there are a few different one in the vostro 1015
I have a very similar problem with my samsung r710 a06 that was a vista 32bit machine and I put windows 7 64bit from technet plus and its fine but the lack of 64bit drivers causes me problems like putting a display driver on my laptop causes windows to fail but I dont have any problems with my wifi or nic