help: jquery mouse position

[akanesakura]

hi everyone,

i'm new to jQuery and javascript could someone help me how to do this effect? please see image below.

http://i38.tinypic.com/ztesra.jpg

i want the blue arrow to follow the mouse pointer position but only the x-axis of the mouse or left and right position. i only want the blue arrow to follow when the cursor is inside the dark gray background.

[Nile]

I can probably do it, but I don't have any time whatsoever, post it in the paid forms[if you can], I'd say something like this is payfull.