Installed Parallels build 5160 today on a clean install of 10.5 Leopard. Issues so far: Hard drive containing Bootcamp partition disappears from finder when it is assigned as a second hard drive in Windows XP Guest OS and is unrecoverable until a reboot (of Mac OS). Random crashes, including several that needed a hard reset (shutting down using the power button). Drivers failing, file systems timing out. Windows XP will not shut down after use (Parallels needs to be killed via a force quit) None of the above happened in Tiger. Let me emphasize that this is a clean install of retail Leopard, on a factory standard 2.66 Quad Mac Pro, with nothing else installed at this point except iWork. If it was going to work, it would work on this machine. SWSoft need to start issuing some clearer guidance that the latest build is not even what I would consider beta ready. If you rely on Parallels, I would recommend sticking with Tiger until further improvements are made. Fortunately, the machine I tested on is just a spare.