ComputrWorld: Be it business or pleasure, most of us have our cell phones handy at all times. Those phones are full of vulnerabilities which are ripe for viruses. Some people change apps faster than their underwear; some of those apps act as a Trojan Horse carrying malicious code. Although some software security experts expect smartphones to be a tempting new target for hackers, F-Secure reported there haven't been more than 500 mobile phone viruses so far. What do we have to thank for staving off the upcoming smartphone attacks? Windows XP.