You just upgraded to a new version of your favourite application which claims to be even more beautiful than the older version thanks to antialiased fonts. But unfortunately there are no more decent fonts. Your new gvim allows you only to choose between these strange fonts which might be good for writing a document in OpenOffice.org but certainly not editing source code in this wonderful editor? You just want your good old 'Fixed' font back?
The solution
It's because GTK2 is using a new font system called 'fontconfig' (along with the Xft-Library). All you need to do is to tell 'fontconfig' where it has to search for your old fonts so it can offer them for you to use.
Edit the configuration file which is probably /etc/fonts/local.conf (or /usr/etc/fonts/local.conf) and add the following line inside the <fontconfig> block:
<dir>/usr/X11R6/lib/X11/fonts/misc</dir>
Additionaly you might also want the following lines: