I maintain a machine much like the one to be used by your son. You are right to give up on trying to get these games working in Wine. Even if you succeed, the next patch might break it. It creates an unreasonable amount of recurring effort, which you can avoid entirely for the cost of an OEM Windows licence, which is really, really cheap in comparison. Sure, this is not what Stallman would say, but then he does not support PCs for a family.
Here are some suggestions:
1. Windows 7 on a new laptop.
2. Install Microsoft Security Essentials. It's free (beer). Don't bother with Norton.
3. Create a regular user account for your son. Ensure the account is not able to modify system files without asking for the admin password. This prevents most of the nasty things malware tries to do. WIndows security is actually really good these days.
4. Order a Blizzard authenticator to go with WoW. This excludes more nasty things that malware might do... just in case!
5. Back up the machine after you install the games but before you hand it over to your son. Use backup software that will generate a disk image like Macrium Reflect Free Edition. Restore this disk image from a live CD (Reflect can create one for you) if your son has any problems. You have to use a full disk image for Windows because restoring an install is not just a matter of copying the files and rerunning update-grub.
6. When working with Windows, use the same patience you have to use when working with an unfamiliar Linux distribution. Don't expect everything to be straightforward or logical, and be pleasantly surprised when it is. The only extra thing you need to beware of, but Linux users do not, is that there are scam sites which offer to "help" you with common problems, e.g. device driver issues, and serve up malware instead of help. Good practice is to research Windows problems on a Linux machine.