For the best security get a Cradlepoint or other router that supports Wifi as WAN and use it with a Verizonwireless mifi device. This provides the added security of a robust firewall between your wife's computer and the internet. Unlimited number of computers can access the internet via the Cradlepoint and you can have it bridging to wireless printers as well.
For the ultimate in security I would use a device running the Apple IOS and not Windows. This will eliminate 99% of your problems of all types. There are very good reasons why only 11% of computer devices currently in use are running the Windows operating system.