downloads and videos stop before completing

I had a problem with Norton 2005 IS corrupting some files. It affected both
browsers, IE 6.0 and Netscape so that I could not get online. I'm not sure
if the downloading and video problems are related. Anyway, Norton told me
what to do to get back on the internet but said I had to upgrade to 2008. I
had just renewed my subscription last month to the tune of $53. and now they
wanted me to upgrade at an additional cost of $70.+ I decided against that
and want to go with Verizon IS, however now I can't get software downloads to
complete and if I want to watch a music video, say on you tube, the video
stops after one or two minutes. If I push the slider, sometimes it will
continue, sometimes not. I even tried to download the verizon pc checkup
tool, and it would not complete. When IE is downloading, the speed starts
fast but continues to slow down until it finally just stops. Now I have
uninstalled Norton so that I can install Verizon, so my pc is now
unprotected. Please help. Thanks in advance.
Jeanne