As you've found out Sniffer Basic v4.5 (the latest version) isn't supported on XP. I also doubt that NAI will release a newer version, as it's at the lower end of their "product set". For your reference - Sniffer Pro v4.7.5 is supported on XP.
What can you do? - Try installing it, you may have issues with ODBC during installation, or when capturing.