I installed and have running Network, Web, and the Standard shields. I would like to add the P2P, since I already have done the installation, how do I this?
Secondly, or more to the point, I download Linux ISO images with a bit torrent sharing program like Azureus or Bit Tornado, is this unsafe ? Or is this behaviour risky enough to justify my adding the P2P shield to avast ?
Thanks,
B.
these files will be scanned by standard sheild once you try to execute them after the download so you still have some level of protection.
If you find you would rather have P2P sheild then you will need to uninstall and reinstall and include it in your install this time.
good luck 
No,no and no!!!
You can just go to add/remove programs click on avast! and select change.Then you can select exactly which components you want to install in your case select p2p provider.You must have internet connection.The selected features will be installed.
Taking a SWAG (scientific wild ass*d guess), if the p2p program is on a Linux ISO that it will be a Linux version and since you have posted on the Avast 4 Home/Pro forum (not the avast 4 Linux forum) you have the windows version of avast 4, in which case a Linux p2p program is unlikely to work.
Also there have been issues with Azureus not conforming to standards and on occasion using the email SMTP ports to connect to the internet. This use of the email ports is obviously scanned by the email scanner and because it isn’t using the email protocol the connection timeout can be displayed. Azureus isn’t currently on the list of supported p2p programs in the avast P2P Shield.