AVR-Chat

How do you go about dimming a 7 segment display (controlled by an
AVR)?  I can't do it via software (already reached the limit), so I'm
limited to hardware.  Basically I don't want the segments getting
dimmer or brighter as more or fewer of them turn on.  Right now this
is my circuit:

http://i6.tinypic.com/1zf3mtl.jpg

and it works well.  I'm just curious if I can do it less
complicatedly.  I.e. one transistor, chip, or whatever.  Need to
reduce parts count.  Thanks,

Brit