Dilbert said most of what I would. But I'd
spec a little differently. Corpse Explosion is a personal thing and that point can be moved to Epidemic if you have issues keeping diseases up, which is made a lot simpler with the Glyph of Disease. If you do not want the disease glyph (i.e. you want to IT/PS more), then go with Dark Death. While I have seen 50/0/21 builds that have performed very well, I don't recommend that build until you're deeper into ICC25 gearing. At which point you will have learned enough to know when it's a DPS increase to try it.
Gem strength. You don't have anywhere near enough ArPen to consider gemming for that yet. The Str vs. ArPen thing is Blood dps only though, keep that in mind if you swap specs.
Drop the defensive gear. Hit is way over.... I'm just echoing Dilbert at this point.
The other things I suggest are vital to really improving your performance:
Research. If you want to min/max and get the most from your toon you need to learn the mechanics more thoroughly. Read Elitist Jerks, Here, WoWHead, even Arena Junkies can teach you things.
Practice. Read a strategy or a gearing plan and practice it. Learn different rotations with different talent/glyph set ups. It's one thing to read about how incredibly awesome AMS soaking is. It's something entirely different to actually do it (omg it's pure sex when you get it working right though!) Knowing the little tricks is what separates good players, from great players.
And finally:
Ignore Gear Score. Seriously. It's a stupid, tangential itemization affect that doesn't really tell you anything of substance about a player. It only tells people the item level you have equipped. I've seen too many people get into raids because of their 5800+ gear score from completely inappropriate gear choices to have any faith, whatsoever, in the current lust-fest that so many pug raid leaders have for gear score. Instead focus on final stats. 263 hit, 26 expertise, and more AP (there is never enough AP), etc.
Good luck!
edit: Gah, typo!
Edited, May 9th 2010 7:01pm by TherionSaysWhat