Like FrankW stated above it is not the plotter or operating system that makes an older plotter function correctly (or not function) but the interface(serial port/comm port/usb adapter) and the driverr for your softare that you use to send files to th plotter.Most newer pc's tend to use a 64 bit operating system and that sort of software uses a 64 bit port addresses to tell the machine where to send the files,where older 32 bit use the older standard 32 bit addresses. the problem facing most users are the drivers used by the cutting software on older versions tend to be 32 bit drivers,and they don't work on 64 bit operating systems,...almost all machines(at least a very high percentage) can be loaded with a 32 bit operating system in oreder to circumvent this problem if 64 bit drivers are not available for the users plotter and cutting software.
Another issue facing some users are proprietary communications port standards,gerber being the foremost that comes to mind. their early plotters needed a special 16 bit isa port card from gerber to work and some have bypassed this with aftermarket adapters.
when it is all said and done most user problems arise when the user wishes to use older 16 bit or 32 bit software rather than pay for costly updates and upgrades to newer 64 bit versions. This is where we get all the suggestions to find an older machine with win 98 and xp installed so the -plottetr will work. The only problem there is it isn't the plotter that will not work but the software which has become obsolete.
Once you get past the software issues there are physical connection issues involving the cableing and port settings that have to be setup to match the needs of the older plotters,...these settings for the most part are not simple for the average user and there are not one button wizards that one can push to make them happen,they require the user become aquainted with some of the more complex settings within the operating system in order for them to function.
When it is all said and done it all boils down to the end users wants and needs, Are you willing to go thru the learning curve and cost of software upgrades in order to make the older plotter work or is it more cost effective to just purchase a newer usb plotter that will load its own driver and setup simply by plugging in the usb cable and waiting on the operating system to do it for you,
All this being said it is not the plotter but the user and software that dictates whether or not a plotter will work on a newer pc with windows 7 etc,....My best advice here would be to check your software first to make sure it is 64 bit compatible and has 64 bit drivers available for the plotter you wish to use. Otherwise a simple fix is to load a 32 bit version of the operating software.