Thanks. What I really meant was, it’s a good idea to upgrade the memory rather than to take the standard memory, which Apple IMHO tends to skimp on (at least, everything built since the Apple //c). :’)
The iMac ran pretty well with a medium load of software (iTunes/Photo, browser, some Finder windows, etc.) with just 1GB RAM. I guess it's all in personal perception of speed. But with 3GB it barely pauses for anything, no matter how much I run (although I haven't run multiple VMs yet -- that'll slow down any system).