2.6 kernel of PWS 500au

[Chris Brotherton <chris@protonlab.net>]

I want to upgrade my PWS 500au (Miata GL w/ usb) and I noticed that testing
now has 2.6.15.  For this system, do I want:

linux-image-2.6.15-1-alpha-generic

or 

linux-image-2.6.15-1-alpha-legacy?

I am not sure if the 500au is considered a legacy system.

Also, is there anything I need to be aware of before upgrading this system to
2.6.15?

Thanks,
Chris.