It's highly recommended to protect your computer against Virus, Malware, Spyware and other potential threats. Microsoft Security Essentials is one of the better, free solutions.
If you use a lot of different usernames and passwords it is difficult to remember all of them. KeePass is an interesting solution where all your passwords are kept in one safe place and protected with one password.
RawTherapee is a free open source application for opening and editing RAW image files. It works on all major operating systems such as Windows, Linux and Mac OS X.
If you are a heavy twitter use, possibly with more then one account, than I suggest you to give Tweetdeck a try. You can arrange, schedule, monitor and manage your tweets with ease.
If any file can not be deleted, then you can use the program LockHunter, which removes the active connections of other applications to that file, which allow you to change or delete file.
