you could try the new version of radiant: gtk-radiant, it still doud q3 but does some of its mods too, the update to gtk may help but i am not sure.
u can download from my site if you want @:
http://www.lochviewwest.plus.com/maps.html
then choose the gtk radiant link
if you don't allready have it i recomend you download pakscape from my site too, it is a very useful free winzip type utility that does pak and pk3 files
AMD duron 1.3G, 640Mb ram, 40Gb HD, ati saphire radeon 9600 atlantis +good creative-labs soundcard, cd-rw + dvd drives.