I think this would be good for leveling to 40.
http://www.worldofwarcraft.com/info/classes/rogue/talents.html?1010000000000000000000240550120050140000000000000000000000000000000]]
You can take more mobs at a time with a combat spec. Especialy with blade fury (which is rad)
I used combat duel swords until lvl 61 then i respeced subt. Im not really into BG's but I like to pvp whenever I pass a alliance. It, IMO, is harder though to pvp combat speced. You really want that ambush and backstab and to beable to stunlock your opponante. Im closer to this now.
http://www.worldofwarcraft.com/info/classes/rogue/talents.html?2050030010000000000000000000000000000000000003502421312301013501151]
I can usually kill a lock and mage in just a couple hits with the new spec and or vanish and shadowstep behind them. SS has a 20 yard reach and 20 sec cd i belive which can catch up to a blinking mage or with proper timing get to a lock before they're dot breaks stealth.