|-=:.ps file from anything (.doc, .ppt etc) under Windows XX:=-|
First of all you need permissions to install a printer (drivers for it actually) on your computer.
So you need to install a driver for one of good standard PostScript printers - there is a number of them among Apple printers for instance. Almost all of them have either "Postscript" or "PS" in their names.
After you have installed driver and probably rebooted your computer (This is my favorite feature in Windows's "Feel Free to Reboot Me" till XP appears) you can use your printer to print to a file from almost any known program. When you print to a file Windows with lack of knowledge what kind of file it is, gives it extension .prn, but it would be just usual .ps.
Good luck. Any comments to this small text are welcome