i changed the font its quite easy even i could do it within two minutes ...
i have not seen a tutorial on this site so i will write how i done it here
first of all download from the market type fresh (needs root ) and install it .
then download andexplorer and install that too
open up type fresh and back up your fonts
search for the font you would like (there are lots on the android themes section of this site )
transfer it onto sdcard/fonts (because these will all be droid sans bold and droid sans , when copying to your sd card choose the keep both files option so you dont lose original font and your new font will be san.ttf and san bold ttf and will both be marked (2) in type fresh
open type fresh and tap dorid sans bold and then select droid sans bold (2) and press ok .. repeat the same steps with droid sans tap and then select droid sans (2)
press ok .
then press menu and apply fonts and then reboot your phone , and your new font will be applied