Time Machine f/size does not match Macintosh HD

Hi:

Is there anyone here interested in helping me to believe this pricey OSX box is as easy as cliaimed and it's not telling me dangerous lies here?

I'm a long time DOS/WIN user porting my personal design and photography business over to a Macbook Pro 17 running OSX v10.6.8 and the learning curve is a bit awkward. Some things are clearly easy, while others are simply not that simple.

For example, I tried to establish a raw system backup before installing third party applications or copying my data over by using Time Machine to back to a hard wired Iomega firewire drive factory formatted to Mac OS Extended (Journaled). The sales people at the Apple store told me that Time Machine makes a true restorable system picture of the native HDD during backups. Maybe true, or maybe he just didn't know what that meant.

So I'm surprised when the backup runs through to a reported completion but the final backup size does not match the stated estimate for a "full backup" which is the same as the Macintosh HD used space.

From a scratch Time Machine backup, the Macintosh HD used space reported by Finder > HD > Info is 22.4 gigs. Time Machine reports an estimate of 22.4 gigs for a full backup just under the progress bar when the backup is running, BUT the progress bar ITSELF only shows 12.9 gigs being copied, and after the backup, the external Iomega drive shows exactly 12.9 gigs less than total space available. So the final backup is NOT 22.4 gigs, but 12.9.

Is this normal? Unless there's some form of compression enabled or the like, how can an estimated 22.4 gigs of system data be backed up to a 12.9 gig Time Machine file on the external drive?

Also, after the backup, I can access the targeted data on the external drive with Finder, as Backups.backupdb > MyName Macbook Pro > [backup date] > Macintosh HD > Applications + Library + System + User's Guide...Information + Users > et. al., but I can't seem to enter Time Machine to see the backup history pictures. I click the app in the dock and nothing happens.

I tried all the Google forums I could find, and a few others have reported the same phenomenon. From instructions from other users I tried deleting the target backup, even the Time Machine .plist and starting over. Still, no one could tell me if the Time Machine backup just saves data and personal/system settings, but NOT a true picture of the native box HD which would include the OS itself. Maybe on restore the OS has to be reinstalled THEN data from Time Machine copied back. I don't know.

I just don't want to think that I've got a safe system picture at the outset only to find it incomplete down the road while trying to restore after a HDD failure or the like.

BTW, I've owned and managed my own systems going all the way back to CPM, through DOS, Win 3.1, 95, 98, 2000, and XP Pro, mostly on Microsoft and Wintel boxes and I've been through a great deal of learning, HDD failures and incomplete system picture backups being only a part. I've worked in design environments using Mac systems, and programming envrirons using Linux, but have not structued a Mac up from scratch as my own administrator until now.

Maybe it's just that the OS is excluded from the Time Machine Backup. Maybe that simple. That's not what the Apple sales guy said, but then I could find no reference to that fact if so.

Confused in Leopard Land, and not even ready to tackle the Lion.