Too blurry? If you're trying to resize it to something that isn't so bad on the pixels (Like say 50%...?) then change the sampling from Bilinear (Smooth) to Nearest Neighbor (Pixelated). Hopefully, the resize won't look ugly at all. I don't have
Paint.NET, so I hope that you can find these features on your own. If you can't, feel free to upload the image here so anyone of us can do it for you.