One client continually getting hit viruses!

Hi,

I have a client that continues to get hit with viruses way to much. This client has AV system that is set to update daily and it appears to be working fine.

Can anyone give me some ideas on how to protect this client? Please be detailed, and offer suggestions on various products, hardware, etc. that could be used together in dealing with this situation.

Thanks for your advice and suggestions in advance.