[s3krit]

You can 'fix' the texture filtering to nearest neighbour in hl by adding the following to userconfig.cfg (should be in a directory called 'valve' in the game's root directory):

gl_texturemode GL_NEAREST_MIPMAP_LINEAR

gl_ansio "0"

gl_round_down "0"

Or just entering those lines in the consoe, preceded by 'set'