Microsoft has advised its Windows Vista and Windows 7 users to disable the Sidebar and Gadget features of the operating systems due to security reasons.These desktop gadgets are based on html 5 that has Internet as a source of information.
Disabling the Windows Sidebar and Gadgets can protect users from security vulnerabilities that may involve the execution of arbitrary code by the Windows Sidebar when running insecure Gadgets.Moreover Gadgets installed from untrusted sources can harm your computer quite considerably and can access your computer's files, it may also show you objectionable content on your screen .
Once an attacker exploits a Gadget vulnerability could run arbitrary code on the part of the current user. If the current user is logged on with administrative user rights, an attacker could take complete control of the affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
Since the Microsoft has issued a warning users all around the world should obey their advise and be on the safer side rather on the vulnerable side as the attacker can intrude into your system and may harm your highly confidential information.
Source : Microsoft