Writing To Often To SSD Will Shorten It's LIfe

Yes, it certainly does.

Never securely erase it. Don't allow your browser cache to be written to it. Don't use it as scratch disk space for apps that require scratch disks. Don't use it as a repository for ANY data that will be written and deleted over and over. Don't copy large files onto it that you will later remove (e.g. movies).

All in all, the lack of TRIM support in OS X makes SSDs quite impractical for a lot of the uses people commonly make of conventional hard drives. When TRIM or something like it becomes available to Mac users, SSDs will make more sense. Maybe by then they'll be priced reasonably, too.

Too late. I usually re-installs the OS X to my MBP every one or two month. Not to mention when installing the OS, i have a habbit of "Zero Out Data".

You should get over both of these habits. Neither one offers any benefit at all.

How do you do that???

You have to set the upper limit of your browser's cache size to a very low figure, ideally zero. Of course this will slow your browser down.

What exactly is "scratch disk"? I think I have seen that term when I was using FCE4.

A scratch disk is just like the pad on which you scribbled the notes and calculations you didn't need to hand in when you took math tests in school (if you're old enough to remember pencil and paper). It's a place for certain applications to write temporary files as part of their normal operations. An app that uses a scratch disk generally allows you to designate one in its preferences. If you have just one disk connected to your computer, that one is used as the scratch disk. If you have more than one connected, you get to choose which one is used. Don't choose your SSD.

So, if SSD/FLASH have so many limititions, why people want them? Just because they run faster?

Yes, and because the people selling SSDs don't advertise the limitations.

The price is also too high.

True. Very true.

What's TRIM?

I'll let Wikipedia answer this one:

http://en.wikipedia.org/wiki/TRIM

If SSD is so vulnarable, who would use them?

People whose preferred operating systems support TRIM. People whose operating systems don't support TRIM, but who've heard that SSDs are fast and haven't done enough homework to understand what the lack of TRIM means. People with more money than sense.

One more question, is there any way that can make SSD and SATA2 work together? Like the 27" iMac, that uses SSD & SATA2. But how do we set it up? Will it be tedious to change the setting for all the programs?

Sorry, I don't understand what you're asking here.

That page is for custom-ordering an iMac, which has bays inside it for two hard drives. You can't order an MBP that way, though you can remove its optical drive yourself and replace it with a second hard drive or SSD (voiding your Apple warranty and/or AppleCare plan in the process).

An SSD at today's prices and with today's drawbacks (both of which will go away eventually) is a big waste of money, in my opinion, for anyone whose MBP isn't subjected on a daily basis to extreme shock and vibration. I encourage anyone who is thinking about an SSD to wait a year for the prices to drop by half and the TRIM problem to be addressed.

Norton's abject inability even to create software to remove its own software properly, let alone make it work usefully, is at the top of the very long list of reasons never to install anything with Norton in its name on any Mac running OS X. Norton software has been an unmitigated disaster on Macs ever since OS X was introduced, and Symantec has never had the good sense to acknowledge its total failure and abandon the Mac market, as it should have done by 2002.

A few years ago, Norton did have the grace to admit that its free downloadable Norton software uninstaller didn't work, and on the download page, right under the link for the uninstaller that didn't work, they gave a laborious 37-step manual procedure for tracking down and assassinating all the myriad bits of Norton garbage strewn about your hard drive that Norton's engineers hadn't been able to teach their uninstaller to find by itself.

There is no average life for a SSD. When yours slows down to the point that it's no longer any faster than a conventional hard drive, get rid of it.

I suppose it might break down, but not in any of the same ways as a conventional drive. And the makers of SSDs are happy to tell you how much more durable they are than conventional drives, as long as you don't want to know exactly how much. In the real world, they just haven't been around long enough in widespread use for there to be much experience with end-of-life SSDs. What is known to happen is that they get bogged down and run slower and slower as time goes by, and TRIM (which can't be done on a Mac, but can on a Windows PC) is the remedy for that.

The Mac OS doesn't enable TRIM — at least not yet. Maybe it will or maybe it won't in the future. If you have a Windoze PC as well as a Mac, you can take the SSD out of your Mac, install it in the PC, and perform the TRIM operation on it, then put it back into your Mac. Some early adopters of SSDs in Macs have done that, perhaps driven by the absurdity of having paid through the nose for something whose performance has rapidly deteriorated in the use they were accustomed to making of their conventional hard drives. Seems to me to be a lot of trouble to go to. I'll wait until TRIM is available on the Mac or made unnecessary by newer SSD design.

now that you mentioned taking out the ssd and putting it in windows pc to trim. is it possible to do that in bookcamp? say i installed win7 on my ssd with boot camp.

No, it isn't. I don't understand why not, but it isn't.