On line poker with an iMac

[newseditor]

I've got an iMac and an iBook for travel. To my surprise, I can't seem to get into the internet poker sites. I get rejected with messages that in effect say: We don't recognize iMacs; only PCs. I haven't tried all the sites, but enough to think this is probably the case everywhere.

Can anyone tell me any internet sites that accept iMac's?