Shadow priest spec.

Streamlined, best dps spec @80, all of the shadowpriests in my guild run this spec.

http://www.worldofwarcraft.com/info/classes/priest/talents.html?tal=050320013000000000000000000000000000000000000000000000320023051223012325152301351

I highly suggest it.

I forgot to say, proper Glyphing is also really importaint. Major Glyphs:

Glyph of Mind Flay OR Glyph of Shadow Word: Death. I haven't tried switching them because on some fights range is very importaint. I use Mindflay

Glyph of Shadow. Crit is importaint to shadow now, so is haste, with this when you crit off of anything (Even Mind Sear aoe) it procs, and since spirit is also a stat you want to build it helps.

Glyph of Shadow Word: Pain. 10% more to mindflay when you're SWP is up? Mindflay renewing SWP? Sounds like a good combo to me.

Minor Glyphs aren't as importaint, nor do they help dps in any real way.

Spell Rotation,
(5x Shadowweaving by the time plauge hits)
VT>SPW>MB>SWD>Dev. Plauge.> Mindflay>Refreshing dots and keeping MB and SWD cast when they're up.

Any real gear help will be found on http://www.shadowpriest.com/viewtopic.php?f=62&t=16992

Shadowpriest.com rocks for information about the class. (They're a little heavy on the adds these days though. :<)