Yeah, that's unusual. If IE7 is hitting 90% CPU and taking up that much RAM, then either:

1. The page it is on has a script or some plug-in that is making IE7 go into a crazy loop. Check to see if the problem keeps happening when IE is on a particular page, even if you haven't touched it for a while.

2. You might have a browser plugin (called a Browser Helper Object or BHO) or an ActiveX control that is doing something. Most "good" plugins don't cause these types of problems, so you might have some spyware/malware. Download and install a program called SpyBot: Search and Destroy:

The home of Spybot-S&D!

In Advanced mode (one of its menu options), you should be able to get to its tools, one of which is a tool to show you what ActiveX plugins are installed, and another tool that shows you the BHOs that are installed. Those tools also let you de-activate bad plugins by unchecking them or deleting them from the list. (Keep in mind that some malware has several different "pieces" to it and will just reinstall itself if you try to remove it)