The K-PACS software is several years old already and neither the software itself nor the installer were created with the new operating systems in mind. Therefore, installing K-PACS on Windows 7 or higher can lead to issues related to user permissions. This may also be the case on your new computer. Make sure to install the software under administrator permissions. Better use a folder for the installation that handles user permissions more freely than the Program Files folder, e.g. install K-PACS directly under C:\. If necessary set the permissions for the installation folder and the database/imagebox folder (if moved elsewhere) so that every user can access, read and write.
Also using a 64 bit OS may create issues. K-PACS is a 32 bit software that cannot fully handle 64 bit systems due to the use of old components for development. So, for instance, you may only see empty study tabs in the viewer, where normally you would see patient information.
So, while you can try using K-PACS on the newer OS, it is correct that you may have to deal with different issues.