What we need for this situation is actually quite simple to make. Take chromium OS, package in a headers only Bitcoin client and a strong encryption program. Create two partitions, one for chromium OS the other for wallet storage, the wallet storage partition is of course encrypted. This entire setup can fit on a small flash drive, and can easily be made into a simple 'Create secure Bitcoin flash drive' program that even a monkey could use (insert flash drive, press button) To make it even simpler you could sell Flash drives pre installed with this software. on first boot the user will chose his password and the encrypted volume will be created. I think chromium OS (or something similar) is best suited for this task for a few reasons.
1) Its lunix based, and as such brings with it a measure of security.
2) It is bare bones, totally lacking anything but a web browser, this may hinder the porting of the Bitcoin client, but it will help security, less programs mean less potential holes.
3) Its fast to start (even off of a old flash drive on a slow machine less than 10 seconds) people do not want to spend 10 minutes just waiting for a single purpose system to boot.
4) Google has already coded the OS to preform a self check on start up and restore it self to a original state if unauthorized changes are made, this is an excellent anti-virus move since all user data is in the encrypted wallet partition
5) Its already mostly coded and its open source, making this task an approachable one, if still difficult.
I think this would be the best approach for the creation of a secure, fast, and simple environment to store and handle Bitcoins.
The main problem with that is, how to teach people to boot a flash drive on a computer. its not even a simple task for even tech people that fix computers. the main problem is that almost every motherboard does it differntly. on 3 of my computers heres how i do it
1: i go into the boot menu and set the flash drive to #1
2: push f12 while booting up and select the flash drive
3: is not able to boot from flash.
I do love the idea though.
As i said in countless other threads, we need specific bitcoin hardware, weather it be a bitcoin certified sticker on cheap laptops, bitcoin credit cards with all the hardware needed on them or even smartphone sized bitcoin devices, or smartphones themselves branded as bitcoin certified.
If we had enough capital, we could buy like 10 of these
http://www.newegg.com/Product/Product.aspx?Item=N82E16834215131 and reformat them and install only the stuff required to have a dedicated bitcoin machine that will only have bitcoin installed. it would also only allow bitcoin related connections so it would be secure against common attacks.