honestly not sure, I'm sure others will chime in.
I tried a free one, LCD Density Changer, but it says it loses the change on a reboot, so I was like :what good is that".
Are you using a DroidX
honestly not sure, I'm sure others will chime in.
If you have root, you can make the change yourself. it's how I did it. I have root, and I picked up root explorer from the market. Then I went into build.prop and changed the density myself. Just gotta be careful in that file or you could really screw yourself up.