You'll be fine, I overclocked my i7 2600k by over 1ghz on a $30 Coolermaster air cooler and over a whole evening of FFXIV and other stuff I don't see a temp over 50 degrees. ATI cards tend to run cooler than nvidia, so you should be fine there too as long as you don't overclock the card too excessively, provided the case is even remotely decent.
I will make the obligatory "Build it yourself" argument though. You could get the same components and save yourself at least a couple hundred bucks. If you really aren't comfortable with it, that's pretty decent for a prebuilt depending on how good their cooling system is. I'm not really a fan of liquid cooling for daily use PCs; it tends to be a bit more failure prone, requires more maintenance and is only really needed if you're going for crazy OCs, whereas the most that's gonna fail on an air cooler is a fan and that's just a screw on replacement. You don't really need to OC these CPUs that much, a OC to 4.3-4.5 ghz will get you 60fps everywhere in FFXIV, even in cities. The only other thing I can really suggest is a SSD (Solid State Drive). With the other components being so high performance, you'll really notice the hard drive as a bottleneck. Since you're posting this in the FFXIV forum, I'll use that as an example. In cities and such, I get a fair amount of stutter before everything smooths out because of everything being loaded from the HDD (I have a 7200rpm caviar black). A SSD will really smooth things out for you and will improve loading times.
I'll also say, don't bother with buying an overclocking package. These CPUs are sooo easy to overclock, and the BIOS is really user friendly. You can just google "i5 2500k overclocking guide", and it'll give you numerous step by step guides. You only really need to change like 2 settings to get to an OC of 4.4-4.5 ghz, which will give you all the CPU power you'll likely need for a long time.
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