Cannot remove virus

A few weeks ago I let some virus in my Dell vista pc, while downloading apparently too many things.  I spoke to

someone at Staples who recomended Norton.  He had stated that because their IS an apparent breach already

existing on my PC that I need to uninstall my free malwarebytes before installing Norton.  My partner is insisting this is

not true.    He installed the Norton and left the Malwarebytes on, I still have the same problem.  Cannot access links from

my email and certain sites, not all links, but this problem started right after I downloaded  (and letting in a virus).  It litterally

started the next day.

Please just give me your advise.

 

 

[edit: Clarified subject.]