CRW supported? JUST sort of. Depends on the camera
Just so it is stated somewhere (which Apple should BTW), I will say it here. CRW is not a universal format. Canon tweaked CRW for each camera it released shooting RAW in that format and as of Mac OS X 10.4.3 and Aperture 1.0 not all them are supported
If someone wanted to use Aperture with a Canon PowerShot G2's CRW, you cannot. Canon PowerShot G2's CRW is not supported. Time for you to leave a note at http://www.apple.com/feedback/aperture.html
Surprisingly Apple's iPhoto but not Aperture's page (or so I think) points to a list of camera's the RAW files of which are supported (seemingly) by all Apple's apps, not just iPhoto:
http://www.apple.com/macosx/upgrade/cameras.html
PowerMac G5 Quad 2.5GHz Mac OS X (10.4.3) 2.5 GB RAM