So first off, WOW is not a graphically intensive game, so a 560 is overkill, however it is still a nice card that will play pretty much everything out there at the highest settings.
Second, this computer will play wow on ultra no problem, except your missing ram, really any brand will do, id recommend 8 gigs as a bare minimum.
Your motherboard is good, however if you have no plans for overclocking or the like, i would get a cheaper one.
The SSD's are a god send for a game like wow. Loading in a major city is a huge improvement with a ssd.
Lastly the CPU is good, however again i would save a bit of money and buy a i5 2500k instead. The benefit of the new cpu's, increased GPU ability and power consumption dont play any real benefit to you. Your 560 will be doing the real work, and power consumption on a gaming computer is never much of a consideration. Also, the i5 2500k's are amazing overclockers if you did want to do that and get a nice performance boost.
However, dont expect performance to always be amazing. with games that are so heavily dependent on bandwidth/latency, you will still get slow down that is in no way related to your hardware. It may be better than it was befor, but it can still exist
Alrite, i see alot of bad or incorrect information in this thread and wanted to throw in my two cents here.
MikeHawk, as you have learned, you can check your in game latency by mousing over the little green/yellow/red bar beside your mana/spirit/whatever pool. This is very important, because "pinging" one server is not the same as"pinging" another. Pinging or the proper term latency, is literally the amount of time it takes for your computer to send a message, and receive a reply back. As you did, pinging google, who has millions of servers, spread all throughout the world, that are not congested, could simply mean you are "talking" to a server in your town, just down the street from you. This is a very small distance and doesnt take a long time to communicate, hence the reason you got a 55 milisecond ping. Talking to blizzards servers, which could be thousands and thousands of miles away from your home, which are under heavy load and network congestion, means you will get a higher ping, and a usual acceptable range for this ping is 100-350 milliseconds. Going outside of this range, you might start to experience "warping" or unresponsive controls. What im trying ot get across here though, is that "pinging" a server isnt a consistent thing, its different for every server you communicate with.
So latency is how long it takes, your bandwidth, which you said was 1.5mb, is the maximum amount of data you can communicate at a time(think of this as like water in a pipe, you have a 1.5 inch pipe and can only force so much water through, if you had a 3 inch pipe you could force more water through faster), however diablo 3 requires very little data to be sent, less than 1% of your connection will be used by diablo. So, bandwidth really isnt a concern.
Now what you are experiencing is happening to alot of people, and it is due to the load on blizzards servers. You will more than likely see this disappear over the coming weeks, and in a month or two will hopefully never see it again. But right now there are millions of people all trying to play this game, and blizzards servers simply cant handle it. So if you get disconnections or warping or whatever else, this more than likely isnt an issue with your internet, but it is on blizzards end. Now with that being said, you could still be a factor in this. For example antivirus programs often contain some sort of firewall software as well, which could be interfering with the games ability to communicate with the servers. Torrenting software as well can wreck havoc on your internet connection, this includes even if the software is not running on your computer, but say a sibling was running it on their laptop which uses the same internet connection.
Lastly i wanted to add in a little tidbit, now im not attempting to defend blizzards decision to make this game require internet connectivity, but diablo isnt meant to be a single player experience. You can play it single player, but it is ultimately meant to be played as a social experience. For an example, the smash brother games are good as single player games, but are meant to be played with friends, they are meant to be a social experience. Or take any mmo, you can play them single player, but ultimately you are missing out on an important aspect of the game. Also taking into account the need to prevent hacks/duping due to the real money auction house, i can see the constant internet connection as being justified in that way. To end this, personally i have enjoyed the hell out of diablo 3 so far, there have been a few roadbumps, but nothing that has soured the experience for me really, and im gonna keep on playing