I thought it would be a great idea start a thread on how much memory is used by your antivirus program and all the apps associated with it. This will help others decide which programs are memory hogs and which are lean.

Please post the exact program name and version. Then post the services and their memory usage. If you are using an all-in-one security suite, please mention that and add up memory usage of all components.

Please list usage in VM Usage KB as reported in Task Manager. Go to View, then select columns and check Virtual Memory Usage. Thanks crahak.

Here are two that I have observed. The memory usage was taken when the system was as idle as possible. Memory usage can vary so this is an approximation.

[Symantec Antivirus Corporate 10.1.7.7000]
Rtvscan.exe 64,748 K
VPTray.exe 5,172 K
ccApp.exe 3,608 K
DefWatch.exe 1,632 K
ccSetMgr.exe 3,808 K
ccEvtMgr.exe 3,984 K
Total 82,952 K

[McAfee VirusScan Enterprise 8.5.0i]
FrameworkService.exe 5,708 K
mcshield.exe 76,144 K
mctray.exe 948 K
shstat.exe 2,144 K
UdaterUI.exe 3,256 K
vstskmgr.exe 7,360 K
naPrdMgr.exe 3,020 K
Total 98,580 K

[Avast Antivirus 4.8.1201]
ashServ.exe 23,544 K
ashdisp.exe 4,204 K
ashMaisv.exe 3,196 K
ashWebsv.exe 20,556 K
aswupdsv.exe 484 K
Total 51,984 K

[Norton Internet Security 2007 10.2.0.30]
AluSchedulerSvc.exe 2,520 K
AppSvc32.exe 13,144 K
ccApp.exe 22,640 K
ccSvcHst.exe 37,428 K
Total 75,732 K

Updated to VM Usage per crahak below.

Your help appreciated.

The mem usage column in task manager isn't the memory usage, it's rather the working set size (not the same thing at all). You want the "VM Size" column if on XP (you actually want what's called "private bytes"). Or use process explorer to have sanely named columns.

I know. It's a very bad choice for that to be the default column, and they're all all named in confusing/misleading ways. Blame MS for that one.

Edit:
NOD32 2.7:
nod32krn.exe 28,768 KB
nod32kui.exe 2,976 KB
Total 31,744 KB (31MB)

Ok, per crahak's suggestion, I converted all to VM usage.

One thing that surprises me is that NIS 2007 uses less memory than Symantec Antivirus 10. Considering that NIS is a firewall + antivirus, I though it would use more. An also the reputation of Norton products... what am I missing here?

SAV isn't exactly lightweight either, and RAM usage is only a small part of the problem. A lot of them are also sucking CPU cycles like there's no tomorrow when they do their job.