It's ridiculously easy to install mods for minecraft.
It amazes me that some people can't drag and drop files in the correct places and delete META-INF (if thats the case)
I bet some of you have some ultra-sophisticated admin settings because it's your parents' computer and you can't modify files in hidden folders or something so stupid.
There is no reason your minecraft would crash if you installed modloader correctly. I've done it for ~10 of my friends and even for people on the internet over teamviewer, and nothing went wrong what-so-ever.