Not to detract from the very valid advice given (need more RAM for sure), when you are looking at the Task Manager, have a look at what process is utilizing your CPU time when it jumps to 100%. To do this go into the Processes tab, and click the CPU column twice (this will sort processes by CPU usage putting the highest use processes at the top). You should have the System Idle Process at the top with around 99% or so. Then launch IE 7 and watch the Task Manager for the process that stalls your computer, watch it for a little while and make sure it's consistently the same process. If it's something ordinary and Windows related, then don't worry about it and just get more RAM (heck get it anyways), but if you see a sketchy named process Google it and get the info on it. You want to make sure that it's not malware or a virus causing your problem. I am not trying to freak you out, cause it's most likely not malware, but it's better to be sure, especially since you notice it when you have IE running.