I'm using a Digi002 with PT8, and running the octane through the lightpipe-in of the 002.
The great thing about getting the M-Audio interface is that if you decide to switch to PT, you'll have that option. However, i know a lot of people who are very happy with Cubase, and for the most part, it's about preference. PT8 has blown me away though. It's definitely worth checking out if you get a chance.
Another option, if you're planning on spending a bit, would be to find a used 002 and have it modified by a company called Black Lion Audio. They take your unit and upgrade the pre's, clock, power supply, converters, etc. (depending on what package you get) and the final result is nothing short of amazing. I've heard a few of these, and to my ear, they're up there with PTHD hardware, if not beyond.