The original Stargate movie had mixed reviews. I really liked it despite it being corny in a couple of places. Some people hated it. It is not necessary to see it to watch the series, but it helps.
There are two versions of the television Stargate SG-1 pilot, called "Children of the Gods". The 2009 version is better edited and was updated to look better. The original 1997 version has a nice nude scene.