As I do not have access to a Vista-loaded machine (which I do not plan to upgrade to), I had no way of testing if Lipikar will be able to run under Vista. As such, I had posted a request on the Lipikar download page (System Requirement section) for the users to get back to me if they had problems with installing Lipikar on their Vista machines.
Finally at long last, I got the feedback I needed. As kindly reported by one of the Lipikar users, Jos Baldewijns from Herk-de-Stad, Belgium on 2nd May 2008, installation of Lipikar failed on Vista, displaying an error message "Unable to register the type Library: Register TypeLib failed. Code 0x8002801C.".
The error points to the inability of the installer to register the VB6 type libraries because of the Vista UAC. These kind of errors are quite common with VB6 applications on Vista only because of Vista's unique and stringent UAC component.
As much as I would like Lipikar to run on Vista - the absence of a Vista machine on my end makes it impossible for me to review the errors being produced and debugging the program to correct them.
So as of now, it is confirmed that Lipikar is NOT "Vista-Compatible", unless and until someone reports otherwise. The System Requirement section of Lipikar download page has been modified to reflect this confirmation.
If you are looking hard for a silver lining to this dark cloud of incompatibility, I can only mention that if I upgrade to Vista on a future date, I may try to release a version of Lipikar which may be Vista-compatible.