Heya,
It really depends on your other components. Your need for application, streaming and multi-tasking are covered with a simple dualcore and even a humble integrated GPU like the HD4200 or series 8 geforce integrated GPU's are more than enough for HD content playback regardless of you using a dualcore or quadcore.
So more appropriately it depends on what all you want out of the motherboard and what else you're going to be using with this machine setup. The motherboard it self will not matter when it comes to doing the tasks you mentioned (exception being an integrated GPU for HD playback, gaming, etc, unless you have a dedicated PCIe card for this that is recent).
Things to consider:
(1) AMD allows you to have AM2+ or AM3 boards for their new quadcores. The difference being the chipset, but at the end of the day, all it means is that you're using DDR2 memory or DDR3 memory. Prices as they are, it doesn't matter which you get because frankly DDR2 is the same price as DDR3 now (oddly). So you probably should just go DDR3 and get a motherboard based on that. And on that note, DDR3 works in pairs with AMD (the triple channel DDR3 is for i7 from Intel only, so don't overspend on a package set of 3 sticks of ram, as it won't do you any service).
(2) Overclocking is all the rage. I like to overclock and underclock (and undervolt) depending on what I'm trying to accomplish. The motherboard very much matters when it comes to overclocking. I assume you may be interested in this since you purchased a `black edition' CPU, which has the sole purpose of overclocking since the CPU multiplier is unlocked for overclocking purposes (giving it the title black edition). Which motherboard you get has a big part in how successful you overclock (and also, your RAM matters here too now that we're on the subject of overclocking).
(3) Components matter. How many drives will be plugged in? Is RAID necessary, and if so, which level of RAID do you need? Do you need integrated WiFi, or are you wired, or do you already have a WiFi addin card? Do you want an integrated GPU for HD playback and light gaming, or do you have a dedicated graphics card (PCIe) that is recent that you'll be using? Do you want ATX or micro ATX? Small case, large case? Will you ever consider SLI or crossfire (likely not, since you said light gaming, but you never know)? What about PCIe slots? Do you need a bunch? 1.0 or 2.0? It matters if you're using various add in cards like soundcoards, controller cards, TV tuners, etc, or if you need old PCI cards (not PCIe) and how many? All these little details matter when selecting the board.
(4) Finally, the last bullet, what price range are you considering? There are good offerings that are well up to $200+ for even an AMD board for someone who is serious into overclocking. Then again, you can get very good overclocking boards for sub-$100. Budget dictates which direction you go, and which features you're willing to spend your money on.
(By the way, I have the x4 955 black edition, so I was in the same boat basically not long ago; I've also used several boards for various purposes, including overclocking and undervolting.)
Very best,
Facebook
Twitter