In that case it's going to be very messy. Why do you need the machine
names? If the users are authenticated against IIS (using NTLM for
instance) then you can get the DOMAIN\USER from the HTTP variables
easily enough, but the machine name is not included. If you have ADS
then it may be possible to use reverse DNS to lookup the machine name
(assuming your ADS DNS is accessible from IIS), but it's going to be
really hard without installing an off-the-shelf component such as
ASPDNS that can handle all the hard work for you.
For instance, something like this might work:
http://www.asp101.com/articles/jason/reversedns/default.asp
However, it may not if the permissions for IIS are locked down, as the
script relies on access to the command interpreter and to write a file
(the example uses a file in the root of drive C, you could use any
location that is writeable). It's the access to the command
interpreter that will likely be the most awkward to organise.