I am running snow leopard 10.6.1 on my mac, why doesn't running "software update" offer to load 10.6.8?

Try installing Mac OS X 10.6.8 manually > http://support.apple.com/kb/DL1399 After installing it, go to  > Software Update to install the Mac OS X Supplemental Update

Please take a screenshot of the following:

Go to the Apple menu which appears in the upper left of the screen, then click About this Mac. Screenshot the window that pops up.

Also under the Apple menu, run Software Update. After it checks for updates, screenshot the window of available updates.