I don't think the '09 parts are up on realoem yet. Theoretically, replacing the drive with an SSD would work and would be a pretty good upgrade, IMO. Don't expect huge speed-ups unless you use one of the very latest SSD products. The previous generation didn't live up to the promises of the technology. The new ones are starting to get there. I see SSD as being the standard in a few years. Of course, BMW won't be using them until the next thing comes along and SSD drives are old hat.
I haven't heard of anyone replacing the drive in the '09 BMWs yet. Love to see if this can be done. Good luck.