Have to much time on your hands ? - Digital Lego

There are some experiences you just can't digitize accurately. Building with Legos is one of them, dammit!

LeoCAD has been doing this for a number of years, if you want an alternative option: http://leocad.org/

I'm betting it does the "plasticy click" noise featured in every other Lego-branded game whenever you put a block down, pick one up, move the mouse...