Computer problem please help?

Okay, could be a whole bunch of different things. Downloading issues could be caused by incorrect settings on your router. Blue screen could be a hardware issue. I've never heard of getting more or less viruses through dial up. You should have a firewall, antivirus and antispyware program installed. As far as opening your case and looking inside, you're not going to see any viruses. You can buy antivirus software from Norton, McAfee or download a free version of AVG.