we use free avira antivirus for protection my computer, maybe you can try to use it.
For 3 choice Free,
Free of charge basis protection:
Avira AntiVir PersonalEdition Classic
Complete protection for the PC:
Avira AntiVir PersonalEdition Premium 19,95 Euro
All around security for the Internet:
Avira Premium Security Suite 39,95 Euro

From free of charge PC basis protection to complete internet protection – at Avira you can find products which perfectly meet your requirements

Use can browse here Or here
I hope so usefull for you, good luck