Gtk 1.5 works worse than 1.4.

I have NVIDIA , version : 2.2.275.00(w/e that means, don't know where to check which model I have), running as an administrator, disabled visual themes = getting http://img185.imageshack.us/i/gtk.png/
and going to Dl gtk 1.5 , and see if works better.

1GB,1.60 GHz

Using Windows 7.
I have windows XP comparety mode ON, but if I turn on GTK Radiant 1.4 , It starts to lagg + has some visual errors as you can see on this picture;

http://img185.imageshack.us/i/gtk.png/

Help please Thanks