IE 7 will be distributed via WSUS in February as an update rollup package. If you chose the default settings when configuring Updating Management in Essentials 2007, this package will not be automatically downloaded and distributed to computers in your company. If you wish to have it distributed automatically, check out this KB article. Its instructions are for WSUS, but will also work for Essentials by changing its Update Management settings to include update rollup packages.
Windows Internet Explorer 7 to be distributed via WSUS February 12, 2008; May require administrator action to manage the rollout