Xena LH and Vegas Pro 8.0c

I'm having capture and playback problems with the above set-up in my Dell Precision workstation T7400.

1) I can capture beautiful video with Machina using either SDI or component Betacam SP input. It plays back fine in Machina too, without any AV sync problems.

2) If I try to capture the same sequences with Vegas, the video captures but no audio.

3) If I import AVIs captured in Machina into Vegas, the video looks compressed (not as crisp) and the audio and video are a few frames out of sync.

Need to dump Vegas for Premier?

Thanks for any help or suggestions!