You probably won't hear this from anyone else, but I recommend not using Windows in this application.
There are several solutions at your disposal. One, is to try to use Standard LabVIEW with this NT Extension (I seriously doubt NT can be made deterministic with any degree of reliability.) You can also try using LabVIEW Realtime, which is available for a number of realtime (true realtime) operating systems, or you can try something else:
Gary Johnson's latest book, Power Programming, 3rd Edition (3e) describes a method for embedding LabVIEW applications on hardware such as a PC104. However, in his presentation, Gary's co-author indicated that realtime Linux could also be used.
There you go, a complete palette of methods to solve your probl
Also, check out LabVIEW RT.