You seem to be ok. Looking through my server with 1.5Gb of RAM the task manager is reporting 2.5Gb. Looking through the processes I find that Store.exe is running at almost 1Gb for my 300 or so users on this server. It seems like the store is seen/reported as memory while it is probably really virtual.

Your inetinfo does seem a little high. Mine is running at about 60mb but then again I use direct SSL from the outside world. I'm not sure how yours would work with the Yahoo but maybe it pulls the mail from yahoo to itself for speed purposes. That being the case I would expect it to be taking more space. My SSL uses the store directly, yours might not.