XP SP3, Vista SP2, 4GB USB drive formatted FAT32 with HP utility.
Installed Beta 4.0 (build 544) on XP, optimized USB drive for performance, allocated USB cache file, everything went smoothly and turned out functional.
Installed 544 on Vista. Added CacheFileName=\\eboostr2.dat at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\EBoost\Parameters in registry as described here, with the exception that \Parameters didn't show up until after reboot: http://beta.eboostr.com/blog/feedback/eboostr-in-dual-boot-xp-sp3-and-vista-sp1/
Vista installation was successful. Optimized USB drive for performance. However, as one might expect, the flash drive is almost completely full from use in XP, and reads full and unusable by eBoostr. Shouldn't the cache be cleared on restart/reboot to allow two different operating systems full use of the entirety of the memory? Is eBoostr dual-boot support facilitated by allocating (and splitting) the space on a USB drive manually? Or do I simply need to free up enough space to build the USB cache in Vista initially, after which both OS will dynamically make use of the entire flash drive (write over each other's caches)?