nod32 is okay, I've been running that for a few months now but I hate with a passion (anal of me I know) things that pop up messages on boot. ESET Nod pops up a nice big box in the middle of the screen on boot which really gets on my ****! I don't like virus software that gets in my face, i'd prefer it just to let me know when there is an issue and to just sit there n do its job otherwise.
I've just gone back today to using kaspersky, or kasperski if you listen to them useless tw@s at PC world. got 3 PCs covered for 1 year for £23 in their sale so can't complain. used it plenty of times before and found it to be one of the best out there.
as for the messages unless you have a paid licence for alfadiag (as I do) I would go with FiatECUScan free version, found it to be very good. gives better fault code descriptions that alfadiag does, certainly when it comes to my new jtdm anyway.