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.
We will install VLC player, which is one of the most versatile players. The biggest advantage of the VLC player is that it does not need any additional codecs.
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 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.