it is not needed.
certainly not for surfing internet.
only thing to watch out for is 'download apps from the market that are not very popular yet and that ask weird permissions and look to good to be true in what they promise'. such apps may ask e.g to see all your contacts while they are a game...
if you like to try out new apps from unknown sources, which you may be tempted to do when this is your first experience with Tablet and Android operating system, it is wise to have some screening/protecting software installed (or don't do it on a tablet you use for serious stuff too).
in principle, the operation system separates what each app does, which makes it difficult for apps to do unwanted nasty things, unless you are lured to give permission to do so. (watch out with Syncing contacts 2 way, for example, if you want to keep business and private contacts in separate programs and accounts, for instance).
