Those four pins above and below the blade are associated solely with the analog side of DVI - something that your projector probably can't accept anyway and that consumer electronics sources don't normally support anyway (I've heard of exactly one DVD player that did).

If you use a VGA-DVI adapter, however, you are using the analog section of DVI. You need to confirm that your projector will even accept an analog DVI signal. If it will, keep those four pins. If it won't, ditch the pins and don't waste money on VGA-DVI adapters that it won't work with.