Link: http://blogs.zdnet.com/security/?p=5225

It could cause you quite a bit of harm,

Microsoft is aware of reports of vulnerabilities in Adobe Flash Player 6 provided in Windows XP. We are not aware of attacks that try to use the reported vulnerabilities or of customer impact at this time but recommend that users install the latest version of Flash Player provided by Adobe.

The Adobe Flash Player 6 was provided with Windows XP and contains multiple vulnerabilities that could allow remote code execution if a user views a specially crafted Web page. Adobe has addressed these vulnerabilities in newer versions of Adobe Flash Player. Microsoft recommends that users of Windows XP with Adobe Flash Player 6 installed update to the most current version of Flash Player available from Adobe.

Nother words the bad boy has more holes than Swiss Cheese - either uninstall it completely or update it.