Can anybody recommed (possibly free) program which is able to print DVD booklets normally = on both sides of the paper so that the result is properly aligned ?
That's going to be difficult...the problem is that a printer only prints on one side at a time, and my experience is that the misalignment occurs mostly because of very slight offset in re-inserting the paper into the printer.
I once had some fantastic templates for MS Word 97 which of course don't work in newer versions anymore. That's what Microsoft calls "compatibility". It was the best think I could find, the sides were really misaligned only a few milimeters, in some cases it wasn't even noticable.
There must be something which can "center" the image correctly on both sides, it's in theory just simple math