Running Vista Ultimate as an upgrade on XP Media Center 05.  My system
is a Dell Inspiron 9300.  It has 2gb RAM.

I am having device driver issues.  Prior to upgrading my XP laptop, I
picked up a spare HDD, and did a full clean install of Vista to ensure
that my critical apps and drivers would continue to work on this
system.  After 4 weeks of testing it out, I went for the upgrade of the
original HDD in the system.  And this is where my trouble begins.

I cannot connect any external USB hard drives.  I cannot connect either
of my digital cameras via USB.  The built-in SD-Card reader does not
work.  According to Device Manager, the drivers were there.
And the Bluetooth will not complete installation (this is the internal card I bought through Dell Parts; it did not originally come with my machine and was not part of my XP system)

I swapped back to the spare drive, and confirmed that everything was in
working order there.  I went bak to my primary system, and uninstalled
the trouble devices in Device Manager.  I removed all the USB
controllers and root hubs,and the SD Card reader.  I expected that when
Vista restarted, it would redetect the hardware, reinstall the drivers,
and all would be A-OK.

Alas, this is not to be.  Now Vista cannot find drivers for devices
that it had previously installed.    It cannot install the USB
controllers, it cannot install the SD Card reader.  Vista keeps
checking Windows Update, but doesn't find the solution there either.  I
have put the Vista install CD in the drive, and there is still no joy.