Is it possible to monitor a file's read and write in vb?

Is this possible?

What I need is, to monitor the files of a virtual machine in real-time to check which VM is slowing down the system. I've researched for a program that can monitor the VM's directly but haven't found any. Now I'm stuck to programming one. And I think it's easier to monitor it's files instead of monitoring directly each VM.

Any help to a freeware program or a start is appreciated. I only have basic knowledge in VB using visual basic express 2005.