is it safe to use AVG anti-spyware

[DavidR]

Yes the two work OK, but if you have the free/trial version the resident/guard process is only available for the duration of the 30 day trial. After the trial the resident and auto update functions are disabled.

[Bluesman]

is it ok to activate the resident shield of AVG anti-spyware?

Yes, it will work fine with avast!

[Will91]

I would use only the on-demand scanners of both AVGas and a-squared.
Three applications won't conflict. If you buy AVGas or a-squared you can choose one of them. Test them and see which one is better for your needs.

Tech:

Why did you say to use only the on-demand scanner of AVG?  Are you aware of some sort of conflict between real-time protection of AVG and Avast?

I'm trying to decide between Webroot SpySweeper and AVG to complete my security package of Avast, Comodo Firewall, and SuperAntiSpyware.  (SuperAntiSpyware is on-demand scanning only and I want real-time spyware protection).

[Lisandro]

Tech: Why did you say to use only the on-demand scanner of AVG?  Are you aware of some sort of conflict between real-time protection of AVG and Avast?

There isn't any conflict, one is an antivirus and the other an antispyware.
But:
1. The AVG guard (resident) is NOT free.
2. You'll take much more resources of the computer having this configuration.
3. If you do not browse dangerously (in sites that are infected), it'll be enough using just avast as resident and, from time to time, make an AVG scanning (on-demand).

I'm trying to decide between Webroot SpySweeper and AVG to complete my security package of Avast, Comodo Firewall, and SuperAntiSpyware.  (SuperAntiSpyware is on-demand scanning only and I want real-time spyware protection).

Well... I think you need to consider the extra-protection and the performance of the computer you want.
Above, my opinion... I know the developers of Webroot SpySweeper or AVG won't like I say they're not *necessary* for the protection... Remember, surf safely