He's 13, since this would just be for web surfing there would not really be anything complicated to do. Throw in Firefox, Libre Office and few other apps. Linux gets complicated when you try to do more "complex" tasks in it. Linux totally sucks for things like user access due to the crappy permission system, for example, but less of an issue for a single user using a single PC, no file shares etc needed and no complicated or specific programs need to be used.
ThoughI just remembered about the feature Ready Boost, I never used it before, but worth a shot. Need to read up on it. Uses a USB stick as ram, basically. The issue that is making this system so slow is that with only 1GB of ram, it is pretty much running off the swap file all the time even on idle. I think I can upgrade to 2GB, but that's it.