Maximum PC

I'm sitting on a still-in-box AMD Phenom II X2 560 Black CPU. It's AM3, 80W & 3.3 GHz. I also have a 3TB pre-flood Hitachi hard drive. I'm trying to decide the best use of this CPU: either a fairly crippled gaming/everyday computer, or a Mini-ITX HTPC.
I've never used mini before, so this might be a fun project if I can find the parts. Finding a reasonably priced compatible mini board with the features I want is a particular challenge. I have not tested the CPU for core unlocking potential, and I'm not sure a mini case would be able to handle the extra heat. I should note that our service is AT&T Uverse, so any CABLECARD add-on would be for naught. Potentially I could just give this computer to my Mom since she has Time Warner.
My goal is to spend as little money as possible, under $300 for a case, psu, mb, mem (gpu optional).
Anyone still futzing around with this chip? Any recommendations for boards? Thanks

A mini-ITX PC might be the way to go in this case, but the problem with mini-ITX systems is that, despite the smaller size, they're a bit more pricey than what you'd expect. But I think if you look around enough, you can get away with spending about $250 for motherboard, RAM, and case + PSU. A $50 video card would be more than enough for offloading video stuff.

Supposedly, I have an Asus M4A88T-I board on the way (coming from Canada, no tracking info), plus some generic SO-DIMM en route from newegg. Need to find a mini-itx case with usb 3.0 AND space for 3.5" drive(s). Thought about the Cooler Master Elite 120 Advanced, but it might be too bulky for my liking. I might need a big case if this CPU can actually unlock the other cores.

I think the SilverStone SG05 w/ 300W PSU is worth it. Comes with USB3.0 headers to boot.

Ok, finally got this thing together. The vendor I ordered the Asus board from turned out to be a bust, but I did get the same board from a different place (more $$ >:( ). I did get the SG05 which is a decent case, but I want to cut off the power supply cables I'm not using.
I got a slim blu-ray ROM drive, 60 GB Vertex 3 HD and Win 7, plus the CPU and 3TB hard drive mentioned before. I was able to get all 4 cores unlocked, but something vexed the large drive (not sure related). I dialed back to 2 cores for now.
I haven't tried any games yet, but have had ZERO crashes, rare occurrences of fan noise (running stocks), and a pretty decent Index score, the only problem is the built-in 4250.
Since it's a small computer, I was thinking of hunting down a ceton card to throw in (almost doubling its value!), or I could get a 6450 for $20 today. I personally don't have a use for ceton, but if we switch to cable or I give it to my mom, that's a different story. If I start installing games, they're probably going to be fairly old titles, so a vid card upgrade shouldn't make too much of an improvement.

Any opinions/ideas where to go from here?