I found a nice thread here that helps you to change the fonts in few steps (using Gscript). it worked fine.
i wanted to change the font again back to the old one. so I deleted the new font from the folder on the SD card and added the old font.
my Milestone doesn't boot now.. It cant pass the Motorola logo.
I pressed the power and the camera buttons and did wipe data and wipe partition.. but still no luck.. :s