Use ASDM. You can manage PIX and ASA with this new Device Manager which is excellent. Also note that the ASA's are the next generation PIX devices and you can do more and they are more powerful and cheaper. Start looking at the ASA's.
Useful Links
Cisco.com Software Center page for ASA software releases:
http://www.cisco.com/cgi-bin/tablebuild.pl/asa
Cisco.com Software Center page for PIX software releases:
http://www.cisco.com/cgi-bin/tablebuild.pl/pix
Regards,
~Glenn
