Yes, you will have to upgrade. For one thing, there never was a mac version for PSE 7 (adobe skipped that one). For another, only catalogs from PSE 9 and up are cross-platform compatible. Buy the boxed version of PSE 11, which gives you both platform versions, install it in windows and upgrade your catalog, then make a full backup to a removable drive, using the organizer's backup command. Install PSE 11 on the mac, then restore it there. Don't buy a download version, since those serial numbers only work on one platform.