poor font rendering in white-over-black (eg Mutt)

[A Mennucc]

hi

I just upgraded my box from woody to sarge
overall the result is OK, but for minor glitches

one problem is that the rendering of the fonts when using Mutt, or any 
other application
that draws white chars over black background, is much worse

I attach a snapshot of the window: as you can see , some characters are 
almost unreadable
(for example the 'o' do not look like circles but rather as squares 
without corners)

any suggestion ?

a.
<<inline: font.png>>