I have 2 hard drives both formated to NTFS, 80 GB ATA which has system partition on it. And SATA 320 GB. Every time i install windows the message [ not xp compatible partition create....... u know the rest. But what i dont understand, is when i remove the SATA hardrive the installation works just fine. Another thing, now windows is installed just fine, i installed windows on my 80 hard while the SATA one is unplugged then i replugged it after the installation is finish. but when i restart the windows wont start the screen just stays in DOS. But when i unplug the SATA 320 GB hardrive it mysteriously starts again with no problem!

My main problem: i want to understand what is wrong with the 320 GB SATA hardrive. What do i have to do so that the two hardrive synchronize together without any problems.

This is the right forum for you question, but perhaps a poor title for your thread.
Maybe you should retitle it to reflect the concerns...
Perhaps something like "SATA drive does not play nice with OS on PATA/EIDE w/NTFS."

Have you looked for other threads dealing with similar issues?

Check boot device priority in BIOS. Your 80gb should be first on the list or at least before the 320gb. In addition once you are in windows you can check the partitions on all the drives and make sure you only have one that is set to "active". Also if you will not be booting off of the 320gb set the "SATA Native" mode to off in the BIOS.