^^ from past experience, lenovos aren't that nice on build quality... well, at least for the laptops back then. But it's been a long while since I've encountered pre-built PCs in general. Been always advised to build my own for the past few builds. But on paper it has pretty nice specs given the price. And I've had a pretty good experience with Dell products -most recently my U2312HM IPS monitor, which is really nice.
I'd say get the one that has better support and warranty, so you'd be set should problems arise in the future.
2o4, if you're coming from Sandy Bridge like I am, it really isn't worth it in getting the new Ivy Bridge CPUs Just like the higher-end Z77 motherboards that have dual/quad x16 PCI-e 3.0 slots, so it's easy to SLI down the road. But then again, it's pointless to go to PCI-e 3.0 since the latest generation cards haven't used up the full potential of PCI-e 2.0.
Coming from a relatively unknown-brand 560 Ti to an EVGA 680 is like night and day -kidding. Well, not quite that different but I'm really enjoying the experience so far.
Inno3D had great hassle-free RMA over here, albeit it only lasting me 5 months on a 1-year product warranty, whereas EVGA offers 3-year global warranty that stays with the card -making it easier to re-sell in a couple of years (a deciding factor for me since I bought the card overseas).
As for the performance aspect, the 680 $&@"$ on dual 560 Tis in SLI, while drawing much less power and having lower operating temperatures. The thing runs about 10C cooler using the stock cooler compared to the 560 Ti. Runs fairly silent up to 65-70% fan speed. Overall, I'm fairly happy with the card. It is a bit more expensive than buying 2 560 Tis, but the overall performance is better. Plus it's easier to resell one newer card than two old generation cards, IMO. But the 560 isn't worthless just yet, wouldn't have bought a 680 before my 560 ti died.
As for the cable management, you should see the backside wiring.
My friend has a Sniper case, too. He's currently in the process of modding it... I don't know why. It's a perfectly good case.