Ok, to honestly and undisparagingly answer the OP.
A proxy server's intended function is not to provide anonymity. Its function is to provide a single, conserved access portal for internet traffic, that can be more effectively monitored and controlled, for network security purposes.
Old versions of proxy software have known security problems, that make them undesirable to use. Despite this, there may be other reasons to want a conserved endpoint, such as management through a firewall, or the conserved use of an SSL interception service, as discussed above. Further, modern server offers will have depreciated old versions of the SOCKS protocol (which is the standard protocol for communication with a proxy), because of these security issues. Vintage computers havent had updates for 30 or more years, in some cases. (Like the afore mentioned mac classics). If they cant use the old protocol, they dont work at all.
'Anonymizing traffic' is a *side effect*. Not an intended function. From the outside, every computer using the proxy server 'looks like one single computer'. Namely, said proxy server.
For a local network, this is not useful at all for 'hiding your identity or location.'
'NT Compatible', is vintage verbiage from the windows world.
What it literally means, is 'Expects an NT style HAL, and an NT style memory heap' These things changed *very significantly* from the designs used by the win9x line of operating systems.
As I initially responded, anything newer than windows ME (which was the last microsoft OS with a 9x style HAL and memory heap design) meets this description.
'In theory', you could run the vintage proxy server on modern windows, but you are likely to have trouble.
Since you want to do this to protect your identity online, I would like to take the opportunity to tell you that this will not be useful for that purpose.
