I really don't understand this obsession with the Z68 motherboards. If you're one of those who just like to try out newfangled features and have the money for it, by all means go ahead. But consider that:
1) The selection of Z68 boards will be much smaller than H67/P67, since it's targeting a niche market;
2) Z68 boards will cost more than H67/P67 boards without any performance improvement;
3) Z68's feature set isn't needed by most people;
If you're one of the unlucky few who want to use integrated graphics on a heavily overclocked i5-2500K (I won't question why), then yeah, I can see reason enough to get a Z68. If not, why even bother? With a dedicated graphics card, just get a P67/H67 already.
Don't even get me started on idiots and their misconceptions of what "SSD caching" will do for them.
Intel NIC isn't really needed; it's definitely better than the onboard Realtek/Marvell chips, but unless you're doing heavy networking tasks (gigabit file transfers, local network database, etc) you will not see any noticeable improvement with an i5-2500 build. A dedicated NIC card will help offload some network-related tasks from the CPU, but even if you constantly approach the gigabit transfer limit over the network, it is a non-issue for the typical user. Get it if your budget allows, but put it at the bottom of the priority list.
The
attainable transfer speeds are pretty similar, and depend on your drivers and NIC settings, as well as transfer protocol used. In case you think the Realteks are real CPU-guzzlers, take a look at
P67 reviews and note the CPU utilisation for Ethernet performance (keep in mind the Asus and Intel boards are using the P67's Intel LAN controller, while the other boards are using the Realtek chip).
tl;dr Realtek is fine and you don't need to feel bad about it.
If you are going to get the X-Fi Xtremeaudio as an entry-level sound card, consider first
the differences between it and the rest of the X-Fi family. For entry-level I'd recommend something else (i.e. non-Xtremeaudio) in the X-Fi series, or go with the Asus Xonar DX/D2. This is a luxury that's only meaningful if you have a sound system to match, so put it at the bottom of the priority list too (above the Intel NIC).
If you find yourself with spare money to spend, go for more memory first. It may seem useless for most purposes, but I presume you will be working with high-resolution stuff in PS. Bump up PS memory cache usage in settings, and you should see some pretty nice improvement. You also get nice cached read access on large files. I haven't had the luxury of running Windows 7 on a high-end PC yet, but I hear it has pretty aggressive caching, so I am simply assuming that the benefits of large RAM I enjoy in Linux apply to it as well.
G.Skill Ripjaws is pretty well-reputed, and should be worth its price. A couple of those 4GB sticks costs about the same as 4x2GB sticks, so it's pretty much a no-brainer if you're going for 8GB of RAM. If you can find DDR3-1600 and/or lower timings (lower timings = better) at a similar price, go for it, but otherwise those timings are hardly a deal-breaker.
Since I linked those RAM sticks, I might as well link some recommended PSUs from the same retailer: Corsair
TX-750/
TX-650. If you plan on going 6970-Crossfire, go with something more power, i.e.
TX-950 (and adjust your budget expectations accordingly).
Why don't I recommend the Cooler Master Silent Pro Gold PSUs? Because the TX-950, despite not having an 80Plus Gold rating,
has comparable power efficiency and much better voltage ripple,
than the Silent Pro Gold 800W. The Silent Pro Gold 1000W is based on the same internals as the 800W, with efficiency at higher loads adjusted as required, but otherwise still performs comparably. And this is supposed to be Cooler Master's top-of-the-line PSU! If that sits well with you, go ahead and get a Cooler Master PSU, but I'm definitely putting my money with more worthy manufacturers.
