I discovered this item in my local Compustore about the time I was shifting to the 'Bus. It was really excellent. I don't use it with Flight Sim 98 or whatever (not that sad) but the airbus MCDU is very well reproduced and most (not all) functions will work well enough to at least let you practice loading the FMC when you're still trying to remember the routine.
http://www.papatango.com/html/PRODUCTS/EFIS/default.htm