You can use the online Software inspecter so you don't need to have it installed.
Malware bytes & Superantispyware - Keep and run a scan occasionally, every two weeks or more if you think you need to. Remember to update before scanning.
That is an installer for something, but not anything I had you use I don't think. Delete it.
Windowsxp-kb884020-x86-enu.exe - Is an update for
Windows XP Service Pack 2 (KB884020) - Did you already install it?
Tinsetup - I don't have a clue what this is. Nothing we use here.
Noscript - That is a Firefox add-on. Where do you see it at?
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Run this
Disable/Remove Windows Messenger to the Desktop to remove
Windows Messenger.
Do not confuse
Windows Messenger with
MSN Messenger because they are not the same.
Windows Messenger is a frequent cause of popups.
Unzip the file on the Desktop. Open the
MessengerDisable.exe and choose the bottom box -
Uninstall Windows Messenger and click
Apply.
Exit out of MessengerDisable then delete the two files that were put on the Desktop.
See if that takes care of the Messenger pop-up in Media Center.
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I am prevented from using youtubr and similar sites
How are you prevented? What exactly happens?