If you died in a space ship or space station at normal atmospheric pressure and temperature you would decompose in the normal way because your body contains all the enzymes and bacteria necessary to decompose you.
If you floated off into outer space in a pressurized space suit you would run out of oxygen and die. Then you would decompose until your space suit ran out of power, lost heat, and cooled off. At that point you would freeze (provided you weren't too close to the sun or anything) and so you would stop decomposing. Eventually your space suit might be pierced by a small meteorite and then you would be exposed to a vacuum. You wouldn't explode but all the water in your cells would vaporise, dissipate into space and you would become freeze dried and float around for years and years until you moved too close to a heat source or fell towards a source of gravity.
Finally, if you accidently fell into the vaccum of space at -270C without a pressurized suit you would become freeze dried very rapidly and the situation would be the same as if your space suit was pierced by a meteorite. (courtesy of Dr Ian MacKay)