Saved as Mpeg- 2 files format. i.e.
Video trye MPEG-2 Video
Attributes: 24 bits, 1440 x 1080 16:9
Frame rate: 25,000 frames/sec
data rate: 25000kbps
I am assuming that you got the above properties by right-clicking on one of the downloaded files within Video Studio -- either with the file in the timeline or in the library window. If so, then it should definitely have also said 'Video Type: MPEG-2 Video, Upper Field First' in the same line. I have a Canon HV20, which, like your Sony, shoots in the HDV format of high definition mpeg-2 to a mini-DV cassette. Anyway, once VS detects the camera, it will (normally) automatically capture using Upper Field First.
Can you also confirm exactly which version of Video Studio you are using, please?
Regarding the disparity in performance between playback in Clip mode and in Project mode, if you click my System button below, you will see that I have a Core 2 Quad 6600, which is pretty powerful. But I too have exactly the sam thing. Playing video in Clip mode is smooth, but in Project mode tends to be erratic, jumpy etc though the audio is smooth. But if you think about it, HDV is pretty demanding (though nowhere near as bad as AVCHD). And in Clip mode, all you are asking VS to do is play back one clip. No problems. But Project mode is asking it to play back a whole project, including all the edits, and do this on the fly. And it seems that any computer, including a Quad, is going to have a tough time doing that smoothly... In addition, the preview window in VS has never been one of its strong points, even with standard definition video...
"Saving as a Ulead Project" is not really doing anything to the video. A Video Studio Project files (.VSP) is only a small text file which tells Video Studio what video clips are included in a project, where they are located on the computer, what editing has been done to them, that sort of thing. In other words, .VSP files are NOT video files in themselves. Almost paradoxically, however, on the othe side, editing video files, while recorded in the .VSP file, do not physically change the original video files. They remain untouched unless you physically apply the changes/edits by choosing Clip > Save Trimmed Video. A new video clip is then saved, and appears in the library window, but the original is still there too, unchanged. The idea is then that you substitute the new file for the bit in the timeline you changed. But I should add that most people don't use this method...
To repeat and expand a little on what I said in my first post, if you want to convert your high definition to DVD-compatible mpeg-2, then with your video project in the timeline, you choose Share > Create Video File > and at this point, I choose Customise (although if your Project Properties are already set to standard definition, and use Upper Field First, you can choose 'DVD' instead of Customise). I make sure the conversion properties are Upper Field First, using a bitrate of of 8000 kbps and with a frame format of 720 x 576. The audio format in my case is normally mpeg layer 2 and I leave it at that, though you can also choose Dolby. Then I click OK and the conversion process starts. It will normally take quite some time. Then when the conversion is finished, I will play back the new mpeg-2 in a software DVD player (I use PowerDVD) to make sure it looks OK.
Note also that after you produce your new mpeg-2, you go to File > New Project. Don't worry about giving your new project a name. The objective is just to clear the timeline of your current project.
Once that is done, you select Share > Create Disc > DVD. The burning module will open. Use the Add Media button at the top to insert your new mpeg-2 in the burning timeline. Then go to the middle of the three icons in the bottom left of the burning screen. There is a little box beside the words 'Do not convert compliant mpeg files'. Make sure that box is ticked (it usually is by default). That way, your already compliant mpeg file will not be re-encoded or importantly, the Field Order changed. Then build your menus and burn.
Believe me, it works with my Canon HV20 and there is no reason it should not with your Sony.