OOH... try this.
Go to Safari and then go to the Safari menu and open preferences.
In here, click on Advanced tab and at the bottom click on Show Develop menu.
Close that and now look in your menu bar. There is a new menu.
Choose that menu and then choose User Agent sub-menu.
In there, choose Internet Explorer for Windows or Firefox for Windows.
Pick a newer version of either.
Then go to OAG and see if the site works for you.
Keep in mind that every page that opens as new, you have to change that User Agent for that page. There is no Global setting. So if this works, and OAG opens a new window when you click on something, you will have to go back to that menu and choose the agent you had before and reload the page.
It may or may not work. But it is something.
The other option, like they said, is to install Parallels Desktop or VMWare Fusion and install Windows in either of those apps. Then you can have Windows and Mac OS running at the same time.
Requires an Intel mac and lots of ram. over 2 GB recommended.