How to flash a ZIP file with Odin? I can't boot my Galaxy Tab 8.9 / P7300 anymore, but Odin still detects a USB connection. So I'm trying to flash a new ROM onto it using Odin. However all I can find on the web are ZIP archives containing boot.img, META-INF etc, while Odin apparently needs .tar or .tar.md5 files.

Can I convert one into the other, or is my idea completely wrong?
.zip files are generally flashable from recovery, Odin's .tars are indeed a completely different format.  If flashing a kernel you can convert them relatively easily (thought I won't get into it here) but it won't work for a whole ROM.  You'll need to find an Odin package.  XDA is your best bet, but see also: Where can I find stock or custom ROMs for my Android device?