http://www.stuff.co.nz/business/money/5423432/Star-Wars-coins-not-a-purchasing-force RLY?

I was going to try to come up with some clever commentary to frame the start of this thread, but I think the video will inspire enough of that all by itself:

http://www.ted.com/index.php/talks/kevin_slavin_how_algorithms_shape_our_world.html

Just don't hate on the dude too much for saying "is is" instead of "is"

Enjoy!

Hi,
I live in New Zealand, where hardware is extremely expensive.
5970s usually retail for over $1000NZD, but today I found a few of these advertised:

Sapphire (21165-00-51R) HD5970 2G GDDR5 PCI-E DUAL DVI-I / MINI DP; Dual Slot Fan Cooler; 32M x 32 GDDR5 512-bit; 725MHz / 1000MHz

for just over $400NZD in a few places.  One of them is a reputable retailer so I'm not thinking "scam", but I am wondering if there's anything I should know about this particular model which makes it so much cheaper? 

Will it still perform effectively (~750Mh/s) for mining?  What about gaming?  Any helpful advice appreciated

So, since I'm a newbie and locked out of the main forum, I'll post my stupidnoobquestion here.  To be fair, it's probably for the best since I'd likely get flamed out for being a repetitive troll otherwise... but... I haven't seen this particular suggestion before:

From http://bitcoinweekly.com/articles/taking-down-the-bitcoin-network :

If it is technically viable, I would suggest that the network be configured now to reject any block from a source with 50% or greater of the processing power. I'm afraid I don't have the technical knowledge to explain how, or even know if it's possible to pre-configure that, but it is something I would like to see, as it would close the only real security hole Bitcoin has.

Is this possible?  Is it a sensible solution?

Cheers.