My Windows 7 machine was recently infected with some trojans via Firefox or Internet Explorer.
Is it safer to browse using the VMware Player + CentOS 6.0 and use Firefox inside CentOS?
If you snapshot your virtual machine, you can do whatever you want on it. Then when you are done, you return it to it's previous state by restoring from the snapshot.
Yes, this would increase security, but it would not make it perfect (no such thing).
Another safe answer is to boot/run CentOS from a Live distribution CD/DVD. Then restart the computer when you are done with your browsing session.