microsoft excel 2010 - How do I enable macros when they are disabled for security reasons?

I upgraded to Office 2010. I have some Excel spreadsheets that contain macros that I would like to run. When I save the workbook as an excel macro enabled workbook it doesn't work. I get an error box that pops up saying that the macros have been disabled.

I checked the macro security settings and this is what I found:

It looks like the only option is to either enable or disable totally. Now the one that is checked it mentions except digitally signed macros. How is this done, and is this the only way I can run my spreadsheets that contain macros?

Answer

You can also enable all macros, the not recommended just explains that if you do download an office file containing macros you don't know it could be dangerous as they could automate certain activities that could be harmful.

I usually just enable all the macros though, get's rid of the "UAC" style restrictions and let's you use Macros whenever you want.