[2005] Graphics API

I am using DirectX9 - DirectDraw to make a game and I realized that I should turn away from this API because it only supports bmps and I would like to use a smaller png file because bmps are very very large so they take up way to much memory space.

So my delema is what API should I use that works with vb.net 2005 or 2008 is fine to. Basically all i need is something that can load pngs and also my game is tilebased to the API needs to be able to the the source rectangle thing that DirectDraw has so you only show part of the image. Also the easier it is to learn to use the better. I heard direct3d can use pngs but from what i've seen a 2d tilebased game would be somewhat difficult in dx3d

So if anyone knows about some good stuff I can use that would be great.