for i7 laptop, if I was you I will choose Y580 instead, the warranty seems better (seems only), and hundreds of bucks cheaper than Asus where I think the difference is not much and even Y480 and Y580 already has GDDR3 GPU.
Asus N56 only wins design and HDD temperature, and the subwoofer which gives very nice bass.. to be honest.
Y480 has JBL speaker, which is considered not bad already.
Software crashing is always not a big deal to worry. Either re-installing software or upgrading software it is ok already.
For buzzing speakers all I can say is if you enjoy music I think you're listening to music at silent places which doesn't need loud volume,
thus lower down the risk of getting buzzing sound 
Also not a very critical problem though, for me it's more like 1/30 songs of chances to get buzzing sound while playing songs.
What to worry if it able to play Gangnam style without any buzzing sound and terribly nice bass 

it's like what others said, you either lucky to get a perfect one or "lucky" one to get faulty one

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Added on August 22, 2012, 9:02 pm
Not every Asus products gets buzzy sound,
Before this I used Asus K40AE, which uses Altec Lansing speaker with SRS surrounds and it is still perfect.
Just that Asus N56 with Bang&Olufsen it is very very awesome compared with Altec Lansing, out of the uncommon-chance-buzzing sound

My friend bought Y480 with JBL speaker, for him it's very very nice too.

(But frankly saying if you want significant difference between this two is the screen, Y580 is gloss LED screen while N56 is matte screen)

Simply say:
1. Glossy - like a mirror, u can see yourself on the screen. very annoying especially when there is light above you
2. Matte - the opposite, you cant see your face. nice for long time staring on ur lappy

Just do what they wrote in this thread lo. Checklist:
1. Touchpad - see working or not
2. GPU - see is GT650M or not (some are GT630M )
3. Test speaker and subwoofer - listen to left and right of the speaker
4. Check keyboard backlight
5. Switch on screen - see got dead pixel or not

ya why not? They ready the pc for you and you must double check everything.
Check the USBs and wifi as well, as they are the most important one to me.
Switch on switch off screen I think it's the hotkey on function key, press Fn+ a logo look like a screen with a big X,
press to toggle on and off.(? LOL)
dead pixel testing you may refer to this website http://jasonfarrell.com/misc/deadpixeltest.php
(hopefully internet available before checking anything? haha)
but most important one double check the subwoofer! and maybe you bring along some songs to check for buzzing sound 

for extra download CPU-Z and HWMonitor or just SIW to check the specs of the laptop,
see if the seller changed your hardware or not

Actually doesnt matter you are in sarawak or not, a lot places have shortage of supplies for this model (not sure hot selling or product order too little  ) but I am Mirian, got mine last week tho

U mean i take some pictures for you or really show you my lappy so u can touch and feel them ? 

Just bought my N56 i5 one, so far so good.
Just now get a BSOD -.- Google chrome sync the app crashed I reopen the app and lol.

Still perfect at the moment, hopefully no prob.

Dammit crashed again. o0o asus

No idea, I'm uninstalling all the asus app - -

It's not that sync problem, just it happened at that very moment.

Keep getting BSOD -.-
Added free 4GB ram on purchase btw.

Okay, I just changed my RAM. (Confirmed the main cause)
Hopefully BSOD won't happen again ><

My touchpad is in perfect state by the way, don't have to go to the edge of the touchpad in order to register clicks.

I don't get what you are trying to tell 

Yeah inside the laptop got something moving lol.
i haven't try the multimedia keys

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Added on August 26, 2012, 10:09 am
Yeah working perfectly now
But windows boot-up fast after inside windows load kinda slow, a lot bloatwares.
My RAM reach 2GB+ upon start up, too much programs on start up

Overall the speaker is awesome, you should get it.