viri \ trojans ?

Hi All.
I have AVG 6 (free) and Trojan Remover 5.0.1 installed.
Both run / update themselves OK.
What I do not understand is why AVG does not check for Trojans and Trojan Remover does not check for Viri.
Are there such basic differences between these type of harmful
intruders, that a single program cannot check/eliminate both
types ?
AVG seems to look mainly at executables and Trojan Remover seems to be looking at the system files.
Is there a product that does both ?
regards

 

You can take a look at this link
http://service1.symantec.com/SUPPORT/nav.nsf/docid/1999041209131106

You will see that there is mention of trojans, and virus trojans.
If you follow the definition to the letter, you could spend a lot of money for a program like Norton Internet Security, or you could get an AntiVirus program, a Firewall program, which will catch some trojans, and Spyware catcher.
I am using AVG, Spybot Search and Destroy, and Zone Alarm. All free.