A quick google search lead me to this item: Pro Elite Wireless Controller for PS3. It still has both sticks in the center but seems similar enough to the 360 controller.

I bought this and got it today, http://www.amazon.com/Pro-Elite-Wireless-Controller-Playstation-3/dp/B003V4AK8E

And its okay, it feels pretty cheap and the sticks have a dead zone. But out of everything i have tried it is the best thing i have come across. Overall i am pretty disappointed. I would kill for a decent replacement.

This is what I use because I'm the same way, I never really got used to the PS3 controller even after having a PS2 and only playing an Xbox 360 a single time. The Power A controller works flawlessly, just keep your Sixaxis controller around in case you ever play a game like Heavy Rain that requires the motion controls.

Ninja edit: Wonderbread_rob hit the nail on the head, I should have looked at the comments before adding mine.