Way to vastly overexaggerate. Is there risk? Yes. But if your power goes out while the drive is writing, whether that option is on or not, there's a chance it'll corrupt that data. All that option does is increase the amount of data that might be lost in such a case.
The option causes windows to make writes only to the hard drive's cache, which the drive will then write to disk at the next possible opportunity. Thus, if the power goes out, you will lose data in that cache as well as whatever it may be writing.
Of course, it should also be noted that the chances of something really getting fouled up by these are rather insignificant for your average desktop. Laptops? I'd turn it off. Batteries die all the time. USB devices? Definitely disable.
I've had this option on for over 8 months now, through multiple power outages and have yet to lose a single file or experience corruption.
As for Vista in general:
A. Most all "tweaks" are useless or eliminate incredibly useful features. People always insist on turning off the Indexing service, while I found that after a couple days of indexing (I let it index ALL my drives) it calmed down and now uses almost no resources. And it provides an incredibly nice benefit (instant searching).
B. Vista uses a lot of RAM for caching. Don't freak out it's supposed to do this.
C. Get the latest drivers for all your stuff. Very important.
Otherwise I highly recommend it. I really like it.