We have a unique and strange situtation here about login procedure to
our website that is written in ASP.

Background:
There are two kinds of users: producers and packers.
They all can access the website using their login information.
Producers and packers can see different options ( reports) on the
website.
Now some producers have given their login information to the packers
so that packers can help them retrieve their information. This
jeopardize our security system, because one packer can see
information of other packers through information of the producers
( because a producer sells their products to many packers ).

Solution:

One of the measures we are taking is to limit a producer to be able
to login from one and only one designated computer. We have thought
about implementing this restriction through IP Address, CPU
identification number or cookie.

My question is can an Java Applet read a CPU Id Number of a user's
computer over the Internet and send us back the number?

We will save it in the database. During each login we will read the
CPU number agin and compare the number in the database with thus
number.
Even if the login info is OK they will not be able to login if the
two numbers do not match.