How much disc space do I really have?

I have been using Mac since Version 8, and this is a first.

Finder and get info on my Apple 512SSD drive shows I have 250GB available, yet Disc Utility shows I have 197GB, and they do change reletavely. I called Apple Support and ran through all the usual troubleshooting techniques without any change.

I did a clean reinstall and everything seemed fine, but as I continue to use it the amounts started showing the disparaging stats and it only gets worse. At it's worst it shoed a 100GB difference in disc space available. In get info and disc utility, the numbers do add up to the total amount of the volume in accordance with the hardware amount.

This went to Apple's highest level of support with a shoulder shrug and, "take it to the genius bar". NO! After using Mac for all these years, I have taught those people a few things. Not trying to be arrogant, just factual. I would dump Lion in favor of Snow Leapord (which it came with) but I've already migrated from Mobile Me to iCloud (iClod).

Is anyone else experiencing this problem. This is what I would really like to know, and if any of the "true" geniuses here can help I would certainly appreciate it.

Thanks

Bill

My stats are current.