This town has a problem keeping hip-hop clubs open. (We're not great at keeping rock clubs open, either, but that's another story.) In the past twelve months or so we've lost Toxic (formerly Club Candela), Seven, the Ambassador and Suite2Fifty. (That last one was known as the Improv Theater and staged both comedy and hip-hop shows.) Dreams is still kicking, thoughand what a year it's had. The club formerly known as the Kastle hosted CD-release parties, the sultry Caf Soul and Rams events. Out-of-town boldfacers including Jermaine Dupri, Janet Jackson and Allen Iverson passed through its doors. Not that we follow stuff like that, mind youthough it seems like half of the club's 15,000 square feet (on three levels) is devoted to VIP areas. Whatever it takes, as long as the place stays open. "They say the average club lasts two or three years," says co-owner William Hart. "But hopefully we can last for 25."