Vegas does a really nice 4/3 to 16/9 conversion built in. If you use Ultimate S you can convert all the clips loaded into a project at once. That's what I'd recomend since that way your titles will be rendered anamorphic directly instead of converted.
Thanks for the info.
The approach I was taking was to try shooting in the squeeze mode of the DVX 100a at 30 frames progressive and then edit in Vegas. I set up Vegas for 720x480 Widescreen with 30p but looked at bit too "strobie" for my taste. I wonder if 24p or 24p advanced will look better?
It does and it doesn't. It doesn't directly work with video files, no, but you can batch-process files, so you can render out a series of BMP's or TGA's, import them as a batch into PhotoZoom Pro (and only the Pro version), batch-process them, and then import the results into Vegas as a numbered still sequence.
It's tedious, but the results are amazing. I up-rezzed DVX footage to 1280x720 to compare pixel-for-pixel against the JVC HD1, and the results were really quite competitive. Nowhere near as satisfactory when up-rezzing to 1440x1080 to compare against the FX1 though.
As far as resizing interlaced video goes, you just need to separate the two fields before resizing and recombine them afterwards. Virtualdub does this quite well. There are options on it's standard deinterlace filter which will convert an interlaced frame into a frame which consists both images half height and side by side. You resize this separated frame to a number that is twice the width and half the height of your desired target. After resizing you recombine the two fields back into a regular interlaced frame. If you want to go from 4:3 to 16:9 at the same time you crop thirty lines each off the top and bottom of the frame before separating and resizing. It works quite well except that the VirtualDub resize filter is nowhere near as good a resize as the Photozoom Pro one is. I would really love is to be able to do this directly in Vegas. A really good spline resize filter with options to separate fields before the resize and recombine them afterwards would be incredibly useful.