I have used various CAD packages to design kitchens etc (one program I own is called CabinetVision worth over $10,000 Aussie dollars) and nothing comes close to SketchUps versatility, speed of design and intuitive nature.
Of course it is great for conceptual drawings. It doesnt work out a Bill Of Materials etc etc. However, because it costs $0 you really ought to give it a try.
Its a really cool tool google acquired it a couple of months back for its google earth integeration function, the best thing about it is it takes so little time to learn!