It's been a long time since fans of Robert E. Howard's barbarian were treated to a decent ''Conan'' comic book. Really, the worst thing to happen to the character was the Schwarzenegger flick; every subsequent take seemed to brand him a monosyllabic lunkhead. Not so in Howard's writings, and not so in this new monthly series that, in the hands of writer Kurt Busiek (''Marvels,'' ''Astro City''), treats him with the dignified respect due one of the towering figures in fantasy literature. The artwork also helps. Rendered by Cary Nord, it feels like historians unearthed a vibrant, bloody tapestry. These are, once again, the days of high adventure.