How to fix this computer?

I'm pretty good with computers, and i went to my grandmas house this week and while im here i've been fixing up everyones computer, and my aunts friend brought her laptop over and i heard it was kind of slow and everything, but i figured it could manage. It's horribly slow, has about 115 processes and cpu spikes from now and then. Was going to install malwarebytes/ Avast Internet Security/Ccleaner, and clean it all up, but it won't even connect to the internet. She has Vista, and the start menu looks different and i can't really find find my way around to a good scanner. (found HP health check, but gave me nothing, and screen went completely white while looking through the resource monitor) If anyone can help me diagnose the internet problem, that would be great. Or possibly a way to put a program on it without connecting to the inernet would be even better. Just ask if you need more information, any help would be appreciated thanks