Hello all!As background: I have a 64 bit Vista Ultimate rig running Virtual PC 2007 (SP1), with a Vista 32 bit VPC set with Shared Networking (NAT) and with Undo disk turned on (i.e. you can dispose of changes after each session). The host machine runs Windows Live OneCare (firewall, AV/AS, etc.), and I run as an Administrator on this machine, but with UAC turned on.The virtual PC is running NOD32 2.7, and I run as a Standard User on this instance. I fully patch Windows when updates come out, and update NOD32 before going on the internet with this virtual PC.How great is the risk of the host Vista OS becoming infected with a virus from the virtual PC in such a configuration? I know its theoretically possible, but how realistic?Thanks in advance!

Hi Barnsie Interesting question. I would think that if both the Host and Client are fully protected, the odds of an infection occuring would be the same as if there were just one system involved? You'll probably get a more informed answer if you post this where the VPC experts answer questions. They will be more knowledgeable about the issues involved, regardless of which operating systems are being used. Here is the link to those groups. Discussions in Virtual PC: http://www.microsoft.com/communities/newsgroups/en-us/default.aspx?dg=microsoft.public.virtualpc&cat=en_US_4596fe15-89c0-4fa3-9c96-22b2f0d124ca&lang=en&cr=US Hope this helps. If this post helps to resolve your issue, click the Mark as Answer button at the top of this message.By marking a post as Answered, you help others find the answer faster. Ronnie Vernon Microsoft MVP Windows Desktop Experience

I'll do that, thank you!

Barnsie Your welcome, glad this helped. If this post helps to resolve your issue, click the Mark as Answer button at the top of this message.By marking a post as Answered, you help others find the answer faster. Ronnie Vernon Microsoft MVP Windows Desktop Experience