there is no similarity to the ships.
The Ori have ships with a vacant piece in the centre (i.e Donut)
Necromungers have ships which land like a foot on planets. Even their transport ships are vastly different.
On a side note - Long live the memory of SG1 and I wish they had of at least done a better finale. And here is some salt for the wound, there will be two more Stargate movies to be made (3 were originally agreed upon, but only 1 was made), and the popular consensus is that is WILL NOT follow the story line of the series, and more than likely will star washed up actors =S
If Kurt Russel makes a comeback i`m going to give up on sci-fi. =P