The software won't work on a 64bit operating system, but there is a trick to make it work. Install version 7 on a XP machine and then directly copy the installation folder to the 64bit machine. Most apps have issues with the installers. After this procedure, download the version 8 update and apply it directly to the installation folder. If it doesn't find anything (states the software isn't installed), then go to the XP machine and type Start > Run > regedit. Locate the software in the
HKEY_LOCAL_MACHINE_Software and export the whole Mathcad folder. Copy the file on the new machine and merge it, then re-apply the update.