Skiing Exercises

Bit of a random question.... but I'm trying to find out any exercises which are good for skiing. I'm going skiing in March so thought if I included some exercises which would help strengthen muscles for skiing now, it's killing two birds with one stone!!

I spoke to a guy in the gym who suggest cross trainer, and two of the leg machines to build the muscle... but does anyone know any good exercises I can do either at home/on the wii!?

Thanks for any help

xx