I use and recommend a simultaneous dual browser arrangement:
You can have as many different browsers open as you want at the same time , without significant slowdowns.
Use FF for general & everyday surfing needs, especially to sites you don't know anything about. Depending on how many plug-in's and add-on's you "hang" onto FF, it's faster than IE, & inherently safer.
Note: Current threats include 'Antivirus 2009' or variants.
Because architecture of the Internet (notably 'Flash' scripting), vulnerabilities are readily exploited in Internet Explorer, & it is now urgent that you use Firefox with current 'NoScript' add-on, which will prevent "opacity-based attacks".
NoScript: https://addons.mozilla.org/en-US/firefox...
Try viewing a site with FF first, and if it does not allow the interaction you require, switch & use IE (but only when it's absolutely necessary), or to use 'Active X' or 'Flash' scripting: but use these at your own peril. Flip back to FF when finished.