It's a good way of getting accused of being a scammer because the people who would buy such a PC are definitely not savvy enough not to download all the viruses and get their coins stolen.
This pretty much.
What you COULD do, would be a live OS, where wallets are preinstalled, that is booted from a USB or external harddrive and which restrains the user from installing anything apart from what is already installed (plus blockchain download and saving addresses, obviously). This way, users would be forced to use it exclusively for cryptocurrency purposes.
You could extend this to being like a netbook, instead of a bootable storage device.