No. In a domain, a computer itself has a password like any user.
The computer need to use that password to authenticate itself on the domain so he can be trusted to open user sessions. That's a fact.
The computer renew its password every 7 days by default as far as I can remeber. In some case, you can freeze that password change by a GPO so it never change.
We have deployed a wifi solution with 802.1X and to avoid user to authenticate themselves, we are using the computer password instead, we are authenticating the computer. 1st, we create a SSL channel by the controler certificate, then we use the MPPE encryption and the computer login (name) / password to authenticate it on the network and allow the network traffic for it.
I wish we could use the same with ISA Server. So we can authenticate computers and then create rules based on authenticated computers, DHCP is then not a problem in that case.
If you play with some OS Streaming technologies like Ardence for example, you can create situations where the password of the machine doesnt match with the account registered in the domain controller, so you can see that the machine is not trusted to open user domain sessions, you have a specific error message for this issue and you need to reset the password on the domain controller and reboot the machine to force the renewal of the machine password.
And with some WIFI technolgy (we have Aruba controllers) you can use the machine account (name and password) to create trusted connections to the firewall to get access to specific VLANs or apply specific security rules for these computers.
But now I'm quite sure ISA Server is not able to do that. It appears ISA is only working with domain user authentification.