http://i.imgur.com/0czST.png
This is what main menu looks like in GOG version. I'm pretty sure this font was wider before, what's up with that? I'm running Russian version of Windows 7 x64.

Yep, looks like it is a bit narrower. Take a look at these screenshots for comparison:

http://img455.imageshack.us/i/scr00001fu0.jpg/
http://img208.imageshack.us/i/helmetmainmenu.gif/
http://img219.imageshack.us/i/fallout108specialoq2.jpg/

Are you running any mods with the game? Running as admin? Compatibility mode? Windowed? Graphics drivers up to date?

But anyway, at least it's not unreadable.

Actually, this was a screenshot from high resolution patch. But the font looks like this even on a fresh install.
As I gather from data files' md5 hashes, GOG version is a UK version. I've replaced data files (master.dat and critters.dat) with files from US version and the font became normal. Either original UK version of Fallout really had different font, or I don't know what happened. Can someone confirm this? :-)

Couldn't say for sure. I'm pretty sure the gog version I downloaded ran in normal resolution before any patches.