The solution for this that I've heard of the most is VMWare ThinApp. Another called
but only for freeware it seems, and by an express consent of the respective app developers. At its best, this process allows one to run even an elaborate office suite from a flashdrive. (That is no doubt much, much easier with an older DOS program such as Xy, for which I recall the procedure has been published here.)
If you have any experience with or insights into this process and its results, I would like to hear them.