Try this if the desktop manager does not pick up the phone:
Browse to "C:\Program Files\Common Files\Research In Motion\AppLoader" then right click on loader.exe and create a shortcut to the desktop. Edit the shortcut properties on the desktop and in the target field add the text "/nojvm" to the end ie so it should look like this: "C:\Program Files\Common Files\Research In Motion\AppLoader\Loader.exe" /nojvm
Then pulll the battery out of the phone, open the shortcut on the desktop. Click on next once, you should see a screen that has a connection drop down box which should be empty because the phone is plugged out. Then as soon as you put the battery back into the phone, plug in the usb cable, after a few seconds it should show something new in the connection drop down box, at that moment click on next and then you should be able to do the software
EDIT: pretty much the same as described in the link above. remember to replace 'program files' with 'program files (x86)' if you have a 64-bit OS