In Fixes for Excel, Gadget flaws, John McBride over at M-Dollar writes:

Among the interesting patches unveiled in Microsoft's August security briefing are those that deal with remote code execution in Excel and three Vista Gadgets. You're not still signed on as Administrator, are you?

On this note, I’d like to mention that I’ve seen many people use admin accounts for casual computing. If not obvious from the article above, that’s never a good idea, no matter which operating system you’re using. Chances are that for casual day-to-day computing, you won’t need admin privileges so it’s best to just set up a non-admin user account for daily usage. Besides, you can always provide admin credentials when necessary.