The X Window products, such as Reflection X from WRQ and XoftWare from AGE Logic (including their recently announced Mac version), let your PC system act as an X server, so you can run Unix X Window applications from a Unix host on the desktop, just like a dedicated X terminal. These products provide a Motif- or Open Look-based X Window right along with Microsoft Windows or MacOS, including features like cut and paste, X11R5 compliance, XRemote, XDCMP, shape extension, backing store, and other wonderful X goodies. For the price of a midlevel PC system and a PC X product you can get the equivalent functionality of a good color X terminal at the same cost, and can still run your PC software.
Unfortunately, running an X server alongside your regular PC system consumes a large chunk of memory, which can set you back $500 to $800 per seat. And while many PC X products will work alongside Microsoft Windows, they often crash or fail to release memory after completion. Also, PC X server products are becoming increasingly dependent upon the Winsock standard, meaning you'll have to provide a dual TCP/IP and NOS protocol stack on each PC -- with all the incumbent management problems, if your NOS TCP/IP gateway does not provide a Winsock layer. Finally, X terminals still perform much better than PC X products (see "PC-based X servers: Features, no pep," August 1994), so think twice before changing that order for X terminals to PCs.