Hi thanhkim,
Firstly, official Lavasoft support for Ad-Aware SE Personal v1.06 ended on 31st December 2007. That is why you are not able to update your SE Definitions as you were used to.
Lavasoft's new product, Ad-Aware 2007, has a Free version which is available from
here or
here.
The product specifications (including which OS are supported) are here:
Tech Specs.
I personally am not familiar with the CA Internet Security Suite - you would only need to worry if it has a real-time protection module and you then purchase a licensed version of AAW 2007 (Plus or Pro) which does have a real-time monitor called Ad-Watch. If CA doesn't, then you could run Plus or Pro without any problems.
Any two real-time programs (be it CA Internet Security, AAW 2007, Spybot S&D etc) running on the same system at the same time may cause false-positive reactions. Much in the same way as one should never have 2 antivirus programs or 2 firewalls.
Regards,
Spike