Best program to redraw an existing map?

[Madmaxneo]

The dimensions of the file are: 60" wide by 58" high, Resolution export:96 dpi with a bitmap width of 5815 and height of 5647. The format is png. I am using true color + alpha. And this is only a small portion of the overall map. I was going to attempt to do the entire city and use it on Maptool. But I will have to do it in pieces. Even now it isn't turning out that great. One of my players has said that there is a way to do it in Photoshop where you don't loose that much resolution when you zoom in like I need to. But he said I would need photoshop to do that. I'm not sure if Xara can do this or not. Am I asking for to much with the size of this thing?
The final file size of this one is 22.4 MB. The resolution I have it set for in my art board is 5814 pixels x 5646 pixels. I hope that is what you meant by the resolution of what I am using. I did convert to jpeg and get a much smaller file result but the poor quality is still there, and little worse. This is only one small part of the city so it looks as though I will not be able to do the whole thing in one map, I will have to do it in pieces.

Bruce
Bruce