@Kvishal:
While I respect everyone's inputs here, I personally feel you should have an antimalware app on your Android. Gone are the days when Android was considered safe from malware - the more popular a platform becomes, the more attractive it becomes for hackers, malware-makers, rogue advertisers and scamsters.
Contrary to what most people assume, the Google Android Market is not completely safe. Unlike the highly-regulated Apple's iOS, you should know that anyone can develop and publish an application to the Android Market, and last year there's been an upsurge in malicious apps on Android:
Android Market free-for-all blamed for malware avalanche • The Register
Thus, malware or bogus apps can infiltrate the Android market easily, as even Google realized last month:
Malicious apps infiltrate Google's Android Market • The Register
However, if you practice common sense, you can keep your Android phone secure without any anti-malware:
1. Do not install non-Market apps or "cracked" apps: no matter how tempting it might look, it is still a risk. Such apps might have embedded malware code, that normal PC antimalware can't detect or clean, and since you are getting these maps from outside the Android Market, Google has never validated its authenticity and safety.
2. Don't install newly launched apps: Install apps from Android market, only if they have thousands of downloads and have many good reviews. Even an unintentionally badly-coded or buggy app can do more damage to the performance of your phone than an intentional malware app.
3. Beware of apps that ask for suspicious permissions. I cannot stress how important it is to be aware of correct permissions needed to be allowed for each app. For instance, a wallpaper app should never ask you permission to your call logs, or a camera app shouldn't track your SMS history.
4. Beware of custom ROMs: These are firmware patches that will replace your existing OS, with a customized OS that has fewer bloatedware and has better apps and performance tweaks. However, unless you download it from a reputed site and it has been reviewed by other users, it is still a questionable risk since the new OS will have absolute control over your phone and data.
The top anti-malware apps in the market are similar to the brands you see on Windows PC, but before you install any security app, see if their free mobile versions has all the required features: antimalware scanner, permission scanner, and preferably, anti-theft and call/sms blocking.
Android Security Product Test (New test From PCSL across 20 A/V apps and using 251 malware samples)
*www.wilderssecurity.com/showthread.php?t=314966
*www.wilderssecurity.com/attachment.php?attachmentid=231002&stc=1&d=1324895988
*www.wilderssecurity.com/attachment.php?attachmentid=231003&stc=1&d=1324895988
Personally I would recommend:
1. Norton or Kaspersky:
They have the best A/v products on PC, and huge R&D divisions to keep on top of mobile malware outbreaks, so they are highly trusted.
2. Lookout or AVG:
They were the first proper antimalware apps for Android, so they have a huge userbase to get feedback on recent malware. AVG has a reputation for false positives, so I don't tend to trust their products, but it is still free. I have been using Lookout from day one, and while it has never caught a malware (probably due to my cautiousness), it has not slowed down my mobile either.
3. Avast:
Recently, Avast Mobile was released, and its free version include privacy reports, call and SMS filtering, SIM-card change notifications, firewall and application management. These freebies might change once Avast launches with a paid app, but for now, it is a very good free app to have.
All the best with your Android experience!