I am running a 3.5 game as a DM.
Approximately fortnightly, though it can vary depending on scheduling hassles.
We're using the PHBs (I and II), DMGs (I and II), MMs (1-5), Fiend Folio, Libris Mortis, Draconomicon, Lords of Madness, Completes (all), Races (all except Faerun and Eberron)...