Apparently new AMD drivers combined with SGminer improvements produce >5 MH/s for 290's.
Always use binaries with caution for trojans/viruses etc - I haven't personally tested any of them.
I couldn't make it work on full speed (installed the recommended driver), but.. I got a BIN created from its kernel and got the same speed increase using an old optimised sph miner.. So guys.. if in doubt.. just search around for BIN files only.