I've been running Windows Task Manager at startup ever since Windows 98 (I think). What I've always done was to create a shortcut, set the shortcut to run minimized, and throw the shortcut in the Startup folder. Another thing I do is to set the option in Task Manager to "Hide When Minimized".
Having recently upgrading to Windows 7, an annoyance was that creating a shortcut from taskmgr.exe resulted in a Task Manager that didn't show processes from all users by default, which I guess is a result of the new UAC model.
My "hack" was to simply configure the shortcut to run as Administrator in the Advanced Options. Now Task Manager defaults to running at startup with the "Show processes from all users" already activated.