freeradius and machine account authentication

[Norbert Wegener]

To restrict access to a lan the network shall be equipped with switches, 
that are capable of 802.1x authentication on a per port basis.
Only client machines with a valid machine account in a central active 
directory shall get access.
As I have never had to do with active directory, I am unsure, whether 
freeradius is suited to be used  for the authentication process.
googling around I found the following assertion:

FreeRADIUS at this time cannot perform machine account authentications,
but it supports proxying them off to another RADIUS server (for example,
IAS, or FUNK)


see: 
http://listserv.educause.edu/cgi-bin/wa.exe?A2=ind0505&L=wireless-lan&T=0&F=&S=&P=613

Is this  true? If not, is there any documentation available, that 
describes the setup?
Which credentials are  used by that kind of authentication: account 
names/passwords , certificates,...?

Thanks
Norbert Wegener