Will a ATAPI DVD A DH16A6S drive work with a ASUS P5Q SE PLUS LGA 775 Intel P45 ATX Intel Motherboard? Or how will I be able to tell if it will work for myself?
Certainly. Why don't you hit Asus's website and download the manual for the motherboard. that should have a photo and/or diagram of your board marked with the locations of the various sockets and components.
I have no idea who "Label Flash" is. I do know however that IDE and ATAPI devices are detected in a sort of interchangable fashion.
If you are unsure of the health of the drive you're going to try and install, I'd try and grab one of these Pioneers from Newegg; http://www.newegg.com/Product/Product.aspx?Item=N82E16827129023 They've had them on sale twice in the past two weeks for $22.95 free shipping. These are pretty much satisfaction guaranteed, and plug and play. Keep checking the page, the sale's usually over the weekend.