Just recently my web browsers (safari, firefox, ie) and mail
have all been displaying a strange font that is really difficult
to read. It seems like it only happens to arial regular, but I
checked the font out and it doesnt appear to be corrupt. I
have know idea what to do.

backup your data and do a full format and reinstall mac os. You could also try buying a font pack for mac that would replace the bad font. You know like 40,000 fonts from office max - $40. Good Luck

Reinstalling OS always works of course but cleaning the
font cache migth be enough. If you need help you can do
that with FontDoctor or Panther Cache Cleaner
http://morrisonsoftdesign.com/
http://www.northernsoftworks.com/

More info
http://daringfireball.net/2005/03/font_caches_gone_wild

I had the same problem after installing new fonts.Bizarre,
unreadable fonts in Safari and Mail. When I copy/paste the
wierd fonts to a new location they look fine.