Too big a security risk.
Second, even on Linux, to keep large amount of coins on your computer, it should be extra protected with some complex security.
A virtual machine with Linux on truecrypt-encrypted hard drive with Bitcoin installed should be enough - it will make life much harder for any keyloggers & hackers to infiltrate it.
With computers it is quite easy to do virtually infinately complex system of safes to store your Bitcoins.
You can create a virtual "room of mirrors" using VM in Truecrypt in VM in VM in Truecrypt in VM in Truecrypt and such.
Such an installation could look like this:
Truecrypt(VirtualBox(VirtualBox(Truecrypt(VirtualBox(Truecrypt(Your Bitcoins))))))
You can store some Bitcoins on every layer of this onion, but you should only store large sums on the last layer.
From now on I'm going to store them on a dedicated bitcoin wallet machine with linux on it. All ports except the bitcoin port will be blocked. It will be connected to the internet only for brief moments when receiving a transaction or when i want to move them to yet a different wallet..and it will always be connected via ethernet, never via wireless (don't trust wi-fi encryption).
This thing with VMs is I read it's possible for the thief to mount the vmware drive and read the contents off the drive. So what you're saying though is to encrypt the entire linux HD with trucrypt? right? not just create a truecrypt image on the VM's HD.