Sping of characters in TAB

[don fisher]

I just upgraded "?" my system to Ubuntu 10.10. The character spacing for 
TAB characters appears to by 1/2 the size of printed characters. So one 
must press the space bar 8 times to move 4 characters.

I do not know how I achieved this, or how to correct it. I would like 
TAB key to advance 4 actual characters.

I was also curious how you add more fonts to the list available under 
Options/Set Default Font menu.

Thanks. I hope this isn't too brain dead.