Have they been to the daycare yet? I know our son was with us when we went for our initial visit, and he got to play around and get comfortable while we were there. I think that helped a lot. If your two didn't get to do this, I would call and ask if you could bring them in for a short time, just so that they recognize it on the first day.
The first time you bring them will be easier for them than for you, but the second time may be a little tough for all of you. My son was 2.5 when he started daycare, and although he absolutely loves it, there are still days when he gets upset when I leave. Are you dropping them off then going to work or somewhere else immediately after? It may help to give yourself at least 20 extra minutes, because you never know if you will need to stay a little bit to calm one of your little ones down.
At our daycare, the girls that work there are great, and if they see that one of the kids is getting upset that mom or dad is leaving, they will take them and get them interested (or at least try) in something else so that their attention is divereted a bit.
Good luck. Kids are lucky when they can be home with mom or dad consistently, but they get so much of the socialization they need from daycare. Hope all goes smoothly for all of you.