Like I replied in the recycled 2-year-old thread, no, it won't do any more damage than may already be in there. When you do a Verify Disk, ANYTHING that may be amiss triggers that warning, ranging from an insignificant stray bit to major damage. The fact that the Mac is well enough to start up, run the utility and come up with that message should lead us to believe it is more of the first rather than the second.
And since you get the infamous "Other" scare too, that leads me to suspect you are using Lion 10.7.x, so let's take it from there. First, deal with the corruption. Read thru this message and maybe take notes or print it out, cause it won't be available while you go thru the steps.
- Restart the Mac into Recovery Mode by holding down the Command R keys prior to the startup chime.
- If a message pops up asking which language to use, select it and Continue.
- Choose Disk Utility at the bottom of the list. Continue.
- Now you're running a copy of Disk Utility like you did before, but not on the Macintosh HD Lion volume. You will notice that the Repair Disk button is enabled. So do that on both the device (xxx.xx GB APPLE HDD xxxxx) and the Macintosh HD volume under it. It WILL say that errors were found.
- Run it again, until no errors are found. Congratulations, corruption has been solved.
- Can and should Repair Disk Permissions while we're here.... Will take awhile. Only needs to be done once.
- Quit, Restart (check the menu) and enjoy a corruption-free Mac.
As for the "Other", it is the catchall that the report uses for everything else. If you check in System Preferences, you will probably find that Time Machine is enabled. The 434GB are partly comprised of local snapshots that TM takes for recovery purposes. Don't worry about it.