Wireless network adapter not working after reinstall

I have a dell vostro 1450. I upgraded from windows 7 professional to ultimate yesterday. After the update i installed all the drivers in c:\dell\drivers . All installed properly except the wireless adapter driver. The install starts n then it automatically closes without completing, sometimes it show an error that "The device may not be present or it may be unplugged" . i have tried running as admin,running in compatibility mode but no use. I downloaded the latest driver drom the dell website and it still shows the same error or sometimes closes without that error. Help needed please :)