This one for example:

PENTAX SDM lenses drive the autofocus system significantly faster and operate more quietly than conventionally driven AF lenses.


They are more quiet, i must agree to that.

Just half of the things i said you're repeating in your comment.

You can setup the green button so that it acts like Av,Tv or green mode on command.

So if you're shooting manually and need to make big changes to get the correct exposure it's simpler to press the green button and let the camera suggest a setting and then work from there.

I don't have a K-X but i believe in the main menu you can change the behaviour of the green button between optical preview and things like that and in the custom menu you can change between Av, TV and green mode so to say. They are being called differently, Tv shift = Av; Av shift = Tv; MTF = green mode

I didn't said that though.
I was talking that lenses Sigma says are macro aren't that macro at all
Just look at the 24-70 f/2.8 macro, that one goes to 1:3.8 sorry but I can't call that a macro.
The DA18-55 can focus closer then most of the sigma macro zoom with his 1:2.9

So i'm saying that Sigma is using the word Macro quite loosely with his zoom lenses...

That's good then, sometimes you can exchange versions for free, i believe Adobe does that if you ask nicely

Reliability is relative though, it depends on what you run and do off course.
I'm running win7 since the RTM version and it hasn't let me down, only once when i installed CS5 over CS4 and removed CS4 afterwards... Adobe deleted some things and trying to correct that things only got worst
Don't know if i can blame windows for that.
Mac might run more reliable just in the way it's build, it's a good and solid OS though I've never doubted that.

Mac is coming with a new OS btw, it seems they are going to make it look and let it work as iOS by the looks of it.
Don't know if that's a good or a bad thing though...

Find that a bit of a strange statement.
If a company doesn't sell their software for Mac i doubt they will sell a Mac version in Asia/Middle East though

We all know that Vista is the most bugged OS of them all, i'm glad i've skipped that one

Can't comment on stability off the Mac but every OS have their problems and Mac isn't an exception.
And please don't be blind and think you're safe for maliciousness software and hackers because you've a Mac.
Currently because there are more windows PC it's far more interesting to attack them but Mac is becoming popular and big companies like Google are starting to use them more, if this trend continues this won't be a reason to get a Mac anymore.
Mac has more holes then Windows 7 does and also the security is better in Windows because they have to, Mac has copied some measured over from Windows but only half way making them less effective. link

Be advice though.
Macro and zooms doesn't mean 1:1 or 1:2 focusing you get with prime Macro lenses.
Macro with zooms mean they are close focusing and some companies are quite lose with that term so check how close it can focus before you buy one for that.

It seems that Sigma is using the term for most zooms that can do better then 1:4.
If we hold that standard than the Pentax;
DA 16-45
DA 17-70
DA 18-55
DA 18-250
DA 55-300
are also macro lenses

the DA17-70 can do 1:3,1 and the Sigma 17-70 macro 1:2.7 and the 18-50 macro 1:3
Just to give you an example.

With what Windows?
They change things quite a bit with Vista and 7.

Why so?

Since you're going from a PC to Mac also count the cost off upgrading your software to Mac versions. Some do it for free, others for a small fee or not and others don't even have a Mac version.
I also looked into Mac but the cost of getting the software and that some of the software doesn't have a Mac version put me off from the idea since i would be running Windows then anyways.
So spending that much for a glorified windows laptop wasn't worth it, for the same price you can get a must faster laptop for just windows.

I'm quite putt off from the idea off a laptop now though, PC are much cheaper to get a powerful one and to keep it up to date so going to get one next year and a netbook or subnotebook to take with me.

I'm behind Tim's idea to do the RAM yourself, with any laptop really.
Every manufactures know how to charge them
If you're going to work outdoors a lot then also get the matte screen, even those are still somewhat reflective though but the normal ones are like mirrors almost.

SSD vs HHD
SSD is faster but they do slow down over time when they get fuller so for now it would be great to use them as the main drive for Mac/Windows and all the programs but keep your files stored on a HHD.
I don't know if you've the option to put two disks in the 17" MBP?

thought it also corrected vignetting these options, my mistake.

vignetting is easy to remove on the pc, i wouldn't worry too much.