For your first question:
I assume you are referring to the Windows PE disk that came with your Service Center kit. Yes, you can use Windows PE on systems running Linux or Vista. It is a standalone bootable environment based on Windows, we typically recommend the use of PE on systems that require Service Center testing in Windows, and are unable to boot into Windows normally. Simply boot from the Diagnostics CD with PE to begin testing.
For your second question:
PC-Doctor Toolbox for Windows showing that Virtual Memory is set incorrectly is a known issue, we recommend that you ignore the error and allow Windows to control the size of your page file.
Please let me know if you have any other questions or issues.
Thank you,
Kris