My own 2 cents, FWIW of course...
1st question is what are you willing to put up with LeetZero? There are several free solutions, but for example you might only be able to update once a day or something, or with Microsoft's Security Essentials you do without a Firewall or several other features that were included in their pay product (before they pulled it off the market). Other AV packages might ask you to put up with a pretty heavy load on your PC/laptop, some are not intuitive at all, especially if you set the firewall Not to let everything pass. Some are prone to false positives, though their fans often seem to think that's evidence that they work. :-) Comparisons on this site might be helpful: http://www.av-test.org/en/tests/test-reports/ , & there's always shadowserver.org, with lots of real-time stats on what's stopping what malware how well.
Normally I'd include a caution on how difficult it can be to remove all traces of an AV installation -- it can go beyond just files & registry entries, e.g. CA once set the HKCR section of Windows' registry to protected!... I could add new apps/entries, but any update/upgrade would fail till I figured out what happened. But the Ashampoo app sits on top of Windows more-or-less, without all the effects you'll get with most AV software.
At any rate, I'll sum it up saying that if there's something better rated that you'll actually use, rather than set minimal security so you don't have to bother, get it -- I've seen most all of the big names [including Norton] on sale for as low as $0 after MIR. There are probably some comparisons out there, but I've never seen Emsi or Ashampoo AM rated alongside the competition -- I would think if they performed respectably they'd be handing copies out to every AV testing site possible.