Hmm did heroic Halfus last night... it was my first time, but my guild's second. They actually used 3 tanks for it... is that common at all? The hardest part for me is making sure I'm facing the right direction so I can still interrupt Halfus. It's also really obvious how bad an Enhancement Shaman's AoE capability is right now since our first target is the whelps :\.
I usually end up pulling the highest DPS on that fight somehow... I'm really not sure how I outpace the others that are usually close to me on every other fight, but I do around 44-45k typically.
I did notice a problem on Halfus that got worse on Omnotron. Originally, we weren't going to go to BWD because they didn't want to save me to one boss. Understandable, but given I only need the wrists from BWD, and it's not uncommon to see a group with Magmaw and Omnotron down, I'm not worried. What I really wanted was the guild reputation that Omnotron gives. Bastion of Twilight doesn't give much rep compared to other instances. In fact, you only get 5 guild rep ticks (I forget how much it is per boss). Throne of the Four Winds only has two bosses, but you get 4 ticks. Omnotron alone gives 4 ticks, so I asked if we could still do that

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But anyway... the problem that I noticed was how cluttered the middle of my screen became. Especially with two units up at once all having events occur (which causes text to appear on my screen)... it was beginning to block my focus target's cast bar. We were trying to get the no arcane annihilator portion of the achievement, but we (or rather, I) ended up missing one

. I think the next time, I'll just stay on Arcanotron the entire time. I only get about a 6s period where I can't DPS when he puts up his shield, but other than that... I can attack the entire time. Two cast bars (target + focus) and the actual animation right in front of me is pretty helpful. I should also consider looking for an option in DBM that plays a noise when it goes off. I'm significantly faster at responding to noises.
Although, the noises almost messed me up on Halfus! It dings whenever he casts Shadow Nova, but it also dings for a couple other things. So, I had to be careful that I didn't blow Wind Shear on the wrong ding

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Single income, father of 2, husband. I made choices to fit my rig under a certain price point. SSD would have been nice, but I still needed a FP (ASUS 23" LED 2ms, can't remember model) and speakers (HK Sound Sticks III).
SSD will be a future upgrade.
Oh yah, 1920 x 1200
Can't blame you there. While a SSD is a nice upgrade, it's still somewhat costly and you won't see much benefit in most games. I believe in an Anandtech article, the only game that really showed a benefit was Crysis. WoW's textures aren't as large and I don't think there are as many in use at all times (maybe more with a lot of people with different gear), so on-demand texture loading isn't as big of a problem.
I've honestly become kind of addicted to them... it's great how responsive a machine is with one. I mostly use smaller ones though since games tend to be the big non-volatile memory hog, so they just go on separate drives. Everything but WoW and SC2 go on a Caviar Black drive on my system. My system is actually kind of similar to yours, but I went with the on-board sound, I use ATI and I don't overclock (except Turbo Boost).
But if you're in fullscreen at 1920x1200, your PC won't have a problem displaying everything at full blast. I think you'll
definitely notice a drop in framerates as you could easily see 100+ in a cave or a building, but you step out into Stormwind, which has a
ton of people, and it begins to take its toll.