Help me fix my roomates computer

[spooooonger]

So my roomate is having major problems with his comp so I thought I would check it out to see if I could help. Its got tons of popups and is running super slow. I tried downloading firefox instead of him using IE and when I try to run the setup file it says "file is not a valid win32 setup application" I also tried to download spybot and it says the setup files are corrupted. Can anyone help me fix this thing?