NONE, have used zero anti this or anti that after dropping Norton garbage about 4 years ago.
My protect myself plan is simple. Trading computer is used for that and that only, at approx 1617 est when ES intraday session is over i do a printout of the 5 minute chart and shut the machine down, flip the on/off switch on back of pc to OFF and then flip off the electric supply to the pc. NO FUSS NO MUSS. Reflip the switches to ON about 0900 est the next morning.
I have another pc for trading backup which basically just sits there and smiles at me in wild anticipation of firing it up...............i do maybe once a week to keep it happy and do XP updates.
The "garbage" pc gets the e-mail, browsing, etc chores. Look!!! Stay away from porn, music free downloads (if any still out there) and other so called FREE stuff and you will be fine.
Nothing beats a clean reinstall of the operating system now and then on the garbage box to wipe away any junk. I never need to do backups because i am a trader and not a person to have files, music, photos etc kept in a pc. If i do a clean reinstall on even the trading pc.............which is rare...........i just reinstall the trading platform and other stuff..........no need to backup anything.
Norton etc is for pc users that are new and believe all the scare talk about security so you buy norton etc.............NORTON SUCKED to no end..............that crap does more harn to your pc than you imagine.............BELIEVE IT.
PS: i do not do banking etc on a pc....( use direct withdrawel at the bank for bills).........yes i order stuff but i change the cards number now and then, call up visa etc and ask for a new number or simply tell them it was lost................BOOM, a new card and no one has the number.
KISS
PSS: next pc will have windows 7 but only because improved security stuff built in. Security is nice, where pretty is useless. I fully agree win 7 has better spyware etc protection than xp..........but the days of windows ME are long gone. Anti this anti that software is for rookies. BYE
Nutmeg...........i just read your post.......agree, buy good machine well equipped and you are far ahead of the crowd. I am finally going to get a laptop and get out and smell some more Roses by just riding around and do some trading here and there. Lenovo looks good so far.