Hello again!
I'm also thinking about having Avira's Antivir (Free edition) AND Alwil's Avast (Free edition) both on my machine, but with only one remote protection on (I would turn off the other one, so they would not interfere). Do you think this is a good idea? Or it's a stupid one?
Additionally I'm planning to install some anti-spyware products (free editions): Lavasoft's Ad-Aware, SpyBot's Search & Destroy, MalwareBytes' Anti-Malware and SUPERAntiSpyware, as you recommended.
Do you think that SpyBot's Or Ad-Aware's resident protection could interfere one with another or even with Avast's resident protections?
(I have Windows XP SP2 on a Pentium 3GHz with 1GB RAM.)
I apologise for asking/nagging, but I want to learn as much as possible before installing. Thank you for your answers and your patience.