RvB came out quite a bit before Halo PC came out (hell, it was out before last year's E3).
All those shots are mine.
*edit*
Those are the two new weapons: The fuel rod gun and the flamethrower.
Believe it or not, there is a flamethrower on the xbox version, you just have to have a mod chip to get it. They didnt finish the coding for it and stuff, so it looks kinda stupid.
The flamethrower was already a bad idea for halo pc, though.