I'm hoping someone here can answer these definitively:

• Does putting a VHD file in an NTFS-compressed folder on the host improve performance of the virtual machine, diminish performance, or neither?
• What about using NTFS compression within the guest?
• Does using compresssion on either the host or the guest lead to any problems like read or write errors?
• If I were to put a VHD in a compressed folder on the host, would I benefit from compacting it?

I've seen references to using NTFS compression on quite a few VPC "tips and tricks" blog posts, and it seems like half of them say to never do it and the other half say that not only does it save disk space but it actually can improve performance if you have a fast CPU and your primary performance bottleneck is the disk.