Hardware Installation Troubles

I just got a new computer and every time I hook up a
piece of hardware it starts the "adding new hardware"
like it should. I go all the way through it and then as
it's installing the drivers it says an error occurred and
the hardware was not installed. I've tried this on
several different items. I've also gone to the sites of
the makers of the hardware and downloaded the drivers
from them and it still says an error has occurred. Some
of the items aren't recognized and others work just fine
except that every time you start up the computer it wants
to "find" them again. What am I doing wrong and how do I
fix it? If you can help me I'd really appreciate it.
Thanks.