That case is very sexy. Unique is always a good draw-in
PCI 3.0 at this moment really only has the benfit of alleviating bottlenecks of auxiliary connections. PCI 3.0 compatable CPU's will reduce the problem of PCI switching whereas current mobos are tying a bunch of expansion slots to a limited number of PCI lanes/bandwidth. As far as GPU bandwith, yes, current GPU's cannot saturate PCI 2.0 x16, and I wouldn't expect this to change for a fair amount of time yet. Also, based on your chosen case, a micro-ATX or smaller MOBO is less likely to run into these problems with to many expansion slots sharing PCI lanes.
If you're not hole-heartedly in the hardcore gaming crowd any longer (first step in the rehab process), you might need to settle with the prospect of a "good enough" gaming rig. Desktops still offer a level of cost/performance that laptops cannot touch, afterall you're paying for the "mobile" benefit of laptops.
You might consider starting at TR's "Utility Player" and fine-tuning based on your available funds and a micro-ATX mobo to fit into your Silverstone case (FYI, Intel CPU's are providing higher gaming performance per dollar right now compared to AMD, some AMD fans will likely ague this point): http://techreport.com/articles.x/21164/4
I'm basing the Utility Player recommendation solely on your interest in a ~$170 case and assuming system prices to match similarly. IMO, the "Utility Player" system provides more than adequate gaming performance for 90%+ of gamers out there, representing the "sweet spot" in gaming systems. The Econobox on page 2 of the same article may even be enough for your needs, which is still a respectable system. If you give a rough estimate of how much you're looking to spend in total, we can provide better advice. You might be able to get away with a less expensive setup based on your needs and available funds.. (However, as a warning based on whatever monetary limit you provide, this might require you to abandon your "dream case" by putting function over form) Please let us know if you are really locked into this Silverstone case, that way people wont hastle you with alternatives for less expensive cases.
Main: i5-3570K, ASRock Z77 Pro4-M, Asus GTX660 TOP, 120 GB Vertex 3 Max IOPS, 2 TB Samsung EcoGreen F4, 8GB 1600MHz G.Skill @1.25V, Silverstone PS07B
HTPC: A8-5600K, MSI FM2-A75IA-E53, 4TB Seagate SSHD, 8GB 1866MHz G.Skill, Hand-Built Wood Case