Let's say LE CDs you and you accept the package or whatever and those shitheads come busting in and your whole house is clean as well as your computer except for the fact that you have a Tails .iso file and VirtualBox to run it on your desktop as opposed to having it on USB/DVD? I ask hypothetically because I can't for the life of me make my shitty Windows 8 system boot Tails on a DVD (haven't tried USB), it gets to the "Loading, please wait..." phase and sits there like a piece of trash. I'm not legitimately concerned about this, just curious if they can even use the fact that you have Tails and VirtualBox on your desktop against you if there is nothing else incriminating and they can't prove you ordered the drugs or trace the BTC back to you in anyway and you just happened to fuck up and sign for the pack
smh...
There is practically no point whatsoever (from a security standpoint) in running Tails inside a VM that's running on a less secure platform. The host system can see everything you do on the guest system. If it is insecure, then the guest system is, too. There are some small benefits - Tails has some helpful utilities within easy reach (like GPG), you have some protection against a drive-by malware infection on the darknets... But really, you're still leaving yourself wide open for anyone who can plant some malware on a windows box (hint: that's just about anyone who wants to) to completely de-anonymize you. Maybe that would be LE, or maybe it would just be some Estonian 17 year-old who's threatening to blackmail you, after researching your dox (not hard, after watching you use your computer for as long as they want) and finding email addresses for your spouse, your mom, your boss...
Your computer probably won't boot Tails directly because it's configured for UEFI or "Secure Boot", which can usually be disabled in the Setup/BIOS configuration available when you first start the computer - you want to either disable UEFI/Secure Boot or enable something like "Legacy boot" or "BIOS boot." Generally you repeatedly tap a key when the machine first powers up, frequently F2 or Delete, sometimes F10, Esc, and sometimes some others. It probably says which to hit for "Setup."
At the very least, I sure hope your Windows setup isn't using an Administrator account by default...