I've seen one case, where a computer was put in a rack room and the monitor, keyboard and mouse were successfully extended to the control room... about that far away. I acquired a client station that has its audio switcher connected through a serial line to a computer that has to be over 50 away. I've had no problems with it in over 10 years, but that doesn't mean everything would work under those conditions.
In any case, it can't hurt you to try it out for yourself and go from there. Cables are available from nearly any office supply or computer store. A local shop might even have the cables you need in their "junk" box, and let you 'try before you buy'.