So, I am finally able to use the Boot Camp partition in Parallels 3150 RC2 by creating a custom configuration. This is a welcome fix. However, the disk performance is so poor it is not usable. The disk operation is so slow that I'm seeing beach balls in OS X when there's context switching in Parallels when doing disk intensive operations. Edit: this does NOT happen when using a virtual disk. I'm only getting 26 MBps on reads and an effective throughput of 3.5 MBps on random seek operations. When using a virtual disk (single image, not Boot Camp) I get more than 100 MBps on reads and an effective throughput of > 50 MBps!!! 1) Is there any way to improve the disk speed when using the Boot Camp partition in Parallels? Is there a special setting that can be specified in the config file? 2) Is there hope of the virtual disk driver performance improving? I haven't really looked, but I have a feeling the the PIO/DMA mode of the drive is probably different between the virtual drive and the physical drive. To be clear, I am not talking about the performance difference of the Boot Camp partition when booting over to Boot Camp vs. running in Parallels. Yes, there is a huge discrepency in performance there, but specifically I'm referring to the performance of a virtual disk image vs. a physical Boot Camp partition as the underlying Windows drive in Parallels. Look at the numbers above. There's a 1,000% difference in performance of the virtual drive. Parallels, please advise.