virtualbox.org

I am new to VM and am looking for information on the best set up for the following situation.
My host is Windows 7 (64 bit). I work with several customers through various VPN connections. For one customer in particular, when I connect to their VPN, it blocks my intenet access (ie. my own work email and support ticketing system). I am looking to set up a VM to access their VPN so I can have my own internet and tools available on the host at the same time.
I would still like to use Windows 7 on the guest. Do I still need to buy a 2nd copy of Windows to install on the VM? If I creates multiple VMs for different customers, do I need to purchase a separate copy of Windows for each one?
Can I use the default NAT setting to accomplish this set up or will I still run into the same issue of getting locked out? If NAT will not work, what settings should I use?
With my limited knowledge so far, the one drawback I have seen in VirtualBox is that it appears that my USB drive must be connected to either host or guest. In VMWare, I think there was a solution to this, but $250 seems like a steep price for that inconvenience.
Any other tips would be appreciated.
Thanks,
Cindy

Your question about how many copies of Windows you need to buy is a question about Microsoft licensing policy, which would be better directed at Microsoft. My own feeling is that my VM platform needs its own license, but I don't worry about how many VMs I've cloned, provided I only use one at a time (e.g. I could get the same effect from a library of backup images for my physical PC, and I don't feel that each backup requires its own license).

I don't use VPN, but typically speaking anything more than basic browsing normally requires Bridged networking.

I'm not sure what you're asking about USB. The fact that a USB network can only have one master is a constraint of USB itself, not of VirtualBox. If you used USB drives directly in VMWare then the same would have applied then also. I suggest however that you look into the Shared Folders feature (see the user manual), since I suspect some variant of that is what you were actually using in VMWare.

About the VPN question, you need to configure the VPN server to not send a default route.
That option has various names but is generally labeled under "default route" or "disabled split-tunnelling" and is usually a security feature.

That way you don't require a VM just for the VPN. In case you cannot disable that option, you'll need Bridged mode, as indicated by mpack.