OK i've not seen this thread in a while but it seems that there is confusion over why it is standard to use a horrible pink colour as the backgroun, this is for 2 reasons:
1) Has already been touched upon, when saving as .gif files or .pngs you must set a transparency colour, this pink was chosen as it is almost never used in a regular image so you can almost be universally sure that you only make parts of the image transparent that you intend to!
2) More importantly, in photoshop, if you wanted to get the car on a transparent backgroun again like the layers in the original .psd but yet post it in a .jpg image you can ues a horrible colour like this as the background.
Next, use the
colour selection tool and tell it to select ONLY this pink colour - when you delete this area you have nothing but the car on a transparent background. The problem with the other chaps posting the car on a white background was that if you used this same selection trick on the white colour, you would also get parts of the car deleted that were also white! Since no parts of the car are mental pink, you only have the background deleted
Hope that makes sense