I think you may be missing an actual HDD there, all you have is a 128GB SSD? I doubt that will be large enough for all your needs. Why do you have such a high priority on the crucial SSD exactly? There's potential to save some money there.
If you want to save some money look at getting a P67 mobo instead of Z68 (Sabertooth P67 comes highly recommended). It has the same overclocking potential but without the integrated graphics (which I think will be fairly useless to you anyway + you don't have to manually disable it). Also allows Xfire so don't worry about that.
If you're overclocking then 650W should be fine, but if you want to crossfire (although I wouldn't recommend it) then it's probably best you upgrade to an 850w model. PSUs run most efficiently when at 50% usage, with your current build it'll probably be at 65-70%, which is fine, but you may consider upgrading if you can find extra cash.
I haven't had any experience with Coolit water-coolers, I'd suggest looking for reviews on how easy/reliable it is. Have you used anything like it before?
There's a chart here: http://www.legitreviews.com/article/1292/6/. You may actually be able to finder a cheaper and more effective alternative, then buy the case on its own.
The 6950 is a nice card, but don't get visiontek, it's a poor manufacturer. You really want Asus, Sapphire, eVGA or XFX for radeon cards. Asus preferable!
For HDD, I don't plan to use one as I am networked through 1Gbs to an HTPC which holds every documents. So, it is really just to store OS, apps and save games, and I am willing to clean old games because I tend to play at only one or two at a time.
As for Crucial, it seems to me to be the very best latest generation price/performance ratio. Even C300 would fit, but it is about the same price. Vertex 2 does not seem less expansive and I don't think that I would settle for less unless I get convinced that I would not see the difference.
You are right for P67, but I tend to not see price differences between it and Z68... Again, I am not even sure what mobo-class I need to reach the o/c aimed at. Any specific ideas?
Any concrete PS model at a good price that would fit the recommended power?
For liquid cooling, I have no experience, it's just that the combo with the case seems a good deal, but I don't want any problem...
As for Visiontek, it seems the only reference card that I could find so it has a high probability to unlock into a 6970.
From what I've read in the Z68 reviews they don't offer any advantages on the OCing side of things, could anyone confirm this? In fact in the articles above they show that the P67 has a higher OC baseline than the Z68 boards.
The only concern is that the P67 boards may have had an issue with disabling integrated graphics, however this may be manufacturer-dependent (First page of the Z68 review). If the prices are similar for you, then go for the Z68.
The Crucial SSD is a good build, not denying that! Was more just general SSD usage I was wondering about, but that makes sense if you're willing to reinstall games etc.
The liquid cooling solution they offer isn't typical do-it-yourself kind. Subsequently it is easy to install, but has pretty poor performance (benchmarks in previous post).
Didn't realise the Visiontek board was reference, as far as I know that's all good! Just make sure that it is definitely a reference board before you buy it
For PSU the most popular and reliable from what I've seen are Corsair. Everyone seems to be going with them, and I don't see why not. There may be two Corsair models for each PSU wattage, go for the modular one for cable management (HX models).