On the flip side of Increasing Virtual Disk size is the question of Compression. Both address availability of space. Someone here told me I need to shrink after compressing in the VM for the space to be available to the Host (OSX). I posed my question in terms of using Zip... but then the question of NTFS compression raised itself, and whether best practice would be to compress the whole virtual disk. I'm running Vista and have four virtual disks, two of which are for backing up (no. 3), and archiving (no. 4).

In a Vista virtual environment running on the Mac, is there a best practice that can be suggested, between NTFS compression and Zip compression, and between compressing the entire disks, or just folder(s), or individual files?

EDIT: I've never used compression on a Virtual Machine, and neither on a non-virtual. What I've read makes it seem that Zip compression can't be used for when you want to access individual files within a zip compressed folder. Neither does Zip seem to be offered for whole disk (virtual disks in this case). Though Zip compression is said to be greater compression, NTFS compression seems more sensible to use because you can compress the whole disk and access individual files. However, something I read somewhere suggested that if you use NTFS compression then it's going to eat up greater CPU usage, even when you're not accessing files on the compressed disk. As a VM already puts a good burden on the CPU, I hope this isn't true. What's the pragmatic truth in this, for compressing in a VM without losing access to individual files, without taxing the CPU (if that's even true). Is NTFS compression the best choice, and how will this affect the need to shrink? Will shrinking after turning NTFS compression on be required?