Chris,
The Sony HDR-UX1 can be used with MPEG Streamclip (and the QT plugin) when used in the SD mode. If it was used in the new AVCHD mode, you appear to be out of luck on the Mac at this time.
but which of those files do i convert?
Try them in MPEG Streamclip and see. (I just hope they weren't shot in the AVCHD mode.)
Take a look at:
http://galbraiths.org/blog/2006/12/26/sony-hdr-ux1-camcorder/
Sony make some excellent equipment, but unfortunately, compatability with the Mac is not high on the product requirement list when new products are being designed.
F Shippey