Microsoft released a new hotfix to the public which deals with issues users have encountered whe installing new hardware, specially when installing USB devices. This hotfix is one of many that will be part of the official Vista Service Pack 1 release early next year.
The symptom is when you are trying to install the new hardware you would a message similar to this one:
Windows encountered a problem installing the driver software for your device"
or
"Windows found driver software for your device but encountered an error while attempting to install it."
The cause of these errors is claimed to due to a Infcache.1 file that is in the %Windir%\System32 folder missing, deleted or corrupted. If the Infcache.1 file is deleted or corrupted, Windows Vista does not re-create the Infcache.1 file.This hotfix replaces hotfix 937187. To get the new fix contact microsoft support or try doing the Live Update for vista.