Your build is alright I guess... But I'd rather go with a hybrid Affliction/Demonology build if you are planning on mainly PvP.
Take a look for yourself:
http://www.worldofwarcraft.com/info/classes/warlock/talents.html?3500020511120110000002050330033050100531320000000000000000000000
(Build suggestions and tweaks are VERY appreciated)
That's just a general idea of a PvP build. I'm no expert at doing the hybrid build, I've just seen it from time to time on some Warlocks.
Have fun killing.