Truecrypt 5.0 adds many new features, most importantly Windows system partition encryption. To put it in slightly inaccurate layman's terms, this means encrypting your entire C: drive. Even if you already write your sensitive data to an encrypted space, files are sometimes squirreled away in unencrypted temp space or in the page file where they may be recovered. Using Truecrypt to encrypt your Windows XP system partition will help eliminate this problem.
Update: I did some more testing after this video was produced. I used Photorec to do some file carving to see how secure Truecrypt's Windows system partition encryption was. Photorec was only able to recover two files, one ASP/TXT file and one PCX, but on closer examination both were false positives. They just contained seemingly random data, which Photorec mistook as real file headers. Truecrypt seems to do a very good job of securing the data on your system drive.

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