Home design software is becoming more accessible and feature rich.
One place to experiment is Google sketchup 3D modelling software which is free.
Google also has a web site called 3D warehouse that has collections of models that can be reused.
Check out their furniture collections or cabinets.
Another option is Punch software’s Home Design which includes both Windows and Mac versions.
It is expensive at $200 USD for Architectural Series 4000 but if you are serious about home design or landscaping there is a lot of value in being able to visualize and walkthrough your designs. The Mac version is new and has gotten 9/10 review from Macosxhints.
Another potential option is plan3d which has a website subscription approach at $36 USD per year.
Check out the demos. Over 6,000 models and textures are included which you can resize and change the texture. You cannot create your own objects with plan3d but you can add images from other sources.