Only for completeness of this thread.
After intensive testing I found out that after applying the patch my external USB HDD does hang very often and looses power. This could hang the complete computer. It seems to be related to hal.dll from XP SP1. If we switch back to the hal.dll from XP SP3 and use a patched kernel the computer won't boot anymore. But if we switch back to hal.dll from XP SP3 and install VSuite Ramdisk without adding any ram disks the system boots up fine. By investigating further we see that the driver that seems to solve the problems is rxvstor.sys, this can be installed with rxvstor.inf and installs a new virtual SCSIAdapter device. If we install the included bus driver only, named rxvbus.sys, we get one or more exclamation marks in device manager on USB devices and the problem still persists. We could also install both drivers and it works, but only rxvstor.sys is needed really. The above was verified on two of my systems. To get the drivers simply install VSuite Ramdisk
and look into the program folder. In the end I recommend to use Windows 2003 Server to support more memory on x86, because I do not know what other side effects the patch will have on XP SP3.