Can Malware be slowed or stopped using Power User accounts

I have a friend who has 4 machines on a home network. All of them are running XP Pro, and all the users are logged in as Admin. Some of the software they use won't allow access to limited accounts, and that's why they all login as Admin. It doesn't take long for one of the machines to get infected, and it seems as if the infection spreads over the local network and infects all of the machines. Needless to say I get a call for help when this happens, since they think I'm a geek because I use Linux instead of Windows.

I wanted to ask if setting up the accounts as power users, which will allow them access to software that will not accept a limited account, would it keep the infections localized? I have installed malware scanning software on all the machines, as well as a software firewall. It seems to help, but doesn't seem to stop all the viruses and malware.

Any help will be greatly appreciated. I would hate to have to tell my friend he's on his own the next time a bug gets into his network, but its costing me too much time when this happens.

 

Appreciate the feedback. I figured that would be the case. I was hoping to set up things to try and compartmentalize any infections, but I didn't hold much hope of that. I have tried to stress things such as staying away from Malicious sites, and of course don't open attachments without scanning.