Hi Nate3
This question will open up a can of worms here , everyone's opinions differ as to what they believe is the best antivirus.
I suggest you check out any antivirus you are looking at and look for reviews etc.
If still undecided all antivirus progs will give you a trial , download a trial , see for yourself if it suits your needs , if not , uninstall that one and try another.
I personally use AVG Free Antivirus it uses little cpu usage and has an extensive antivirus data base , worth a look
I wish you luck , dont just rush out and buy , try .
also there are lots of free versions out there also.
Hope this helps