What if every security measure fails...

[dredogol]

Alright... here's another Q...

Option #5... full-blown VM, or a VM sandbox?

I'm debating if I should:
A) Just install VirtualBox (free) to do my all my volatile IM/Browsing, and copy necessary files back to my host PC (no games on VM).
B) Install a sandboxed VM like DeepFreeze or RSS/RVS... and leave my entire host PC vulnerable.

Of course, in both cases, proper user restrictions and policies will be enforced.

Would the VirtualBox route be the smarter method, if all my web-browsing and volatile processes are isolated there... and all the other safer offline and game activities are on the main host pc?
Since games are on the main host pc, all the major performance issues related to VMs won't be an issue in this case.

I have 4GB of RAM , 1TB of HDD , and running a 3.4GHz Quad Core2 processor.

Any thoughts?

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Oh, and 1 more thing...

Since the guest PC is accessing the hardware of the host pc to access the internet, are there malware/rootkits that infect the host pc, completely evading the guest pc in the first place, because the network access is run through the host first?
Not sure if this is possible, because all the packets have to be assembled at the application level on the GUEST pc, but I have no idea if any partial packets can do any harm to the host side at the transport level...