Server -based Anti-Malware

Our network consists of about 20 servers and 50 remote offices. We recently installed Symantec Endpoint Protection. However, the anti-malware portion of the software brings any computer with less that 2GB of RAM to its knees.

The AV portion seems to work well but now we need an anti-malware solution. Is there anything that is more server based rather than client/server based? Or something with an agent that is a little less demanding?

All of our systems go through our main data center and ISA server as does all of our internet connectivity as we are a healthcare firm. Would appreciate any suggestions.

Brian