Bluetooth is a very LOW bandwidth at this time... Version 1 caps out at about 1Mbps while version 2 caps out at either 2Mbps or 3Mbps... Version 1 is also rather short ranged at under 30 feet. The range is also effected by what's in the walls and other 2.4GHz frequency items (just like 802.11b/g is).
Bluetooth version 1 is already obsolete, so if you get the dlink item (or anything like it) you're already missing one of your parameters.
Unless you have LARGE rooms where the speakers are going to be a great distance from the sound source, bluetooth is just going to be a waste of money. For what those adapters cost, you could get an electrician to come in and wire up the room(s) with speaker wires and just use any damned speaker you want.
I actually ran speaker wire for my mother a few weeks back. We put the wire through the ceiling, into her attick, then back down into the kitchen where she wanted a pair of speakers to be. Cost about $20 for the wire and you're hard pressed to see it (matches the walls in the living room where the stereo is, in the kitchen, the speakers hide the wires).
I've yet to hear of ANY home theater setup use wireless speakers. If anything, they use monster cable which has virtually 0 loss between the source and the speakers. With any wireless product, you'll have loss plus you run the [very real] risk of having something else block or conflict with the frequency the wireless item functions on.
Save your money and wait for the technology to mature. For a fraction of the cost of those modules, you can wire up your place yourself. OR get a professional in to do it for you for the same money (or close to it). Hell, most places that sell quality speaker setups will even do the install for free...