If you can find it in your area, the very BEST antivirus client is Kaspersky.
Almost zero false positives, and finds almost everything. A lot of viruses can be Welded, encrypted and compressed to where no other antivirus can find them. I have tested this with 50+ keyloggers and trojans, using PED, PEwelder, and standard Rarring. Nothing beats it.
Panda comes in a very close second in my book. Followed by a 2 way tie with Norton Corporate and Macafee