Well the current version of iPhoto is 9.4.2. so you're a long way behind. The version of iPhoto that can use an Aperture Library is something like 9.3 or thereabout.
Find and download the 9.1 updater. Run it. Then Run Software update again. And probably again after that too.
It doesn't matter because it is at least very close to the "latest."
Yes it does matter because between iPhoto 9.0 and 9.4.2 there have been major changes to the applicaiton and it features. Even between 9.3 and 9.4.
If you can't give us the info we need we can't help you. And yelling at us (all caps) won't help either.
I apologize for "yelling" and will make no excuse for it. I have upgraded to iPhoto 9.4.2 (I have Aperture 3.4.3), but still get the same error message: "IPhoto is unable to open this library. You have opened this library with a newer version of iPhoto. Please quit and use the latest version of iPhoto." All I get is the spinning beach ball.
You should try repairing your library as follows: make a temporary, backup copy of your library if you don't already have one (Control-click on the library and select Duplicate from the contextual menu) and apply the two fixes below in order as needed:
Launch iPhoto with the Command+Option keys held down and rebuild the library.
Since only one option can be run at a time start with Option #1, followed by #3 and then #4 as needed.
Using iPhoto Library Manager to Rebuild Your iPhoto Library
1 - download iPhoto Library Manager and launch.
2 - click on the Add Library button, navigate to your Home/Pictures folder and select your iPhoto Library folder.
3 - Now that the library is listed in the left hand pane of iPLM, click on your library and go to the File ➙ Rebuild Library menu option.
4 - In the next window name the new library and select the location you want it to be placed.
5 - Click on the Create button.
Note: This creates a new library based on the LIbraryData.xml file in the library and will recover Events, Albums, keywords, titles and comments. However, books, calendars, cards and slideshows will be lost. The original library will be left untouched for further attempts at fixing the problem or in case the rebuilt library is not satisfactory.