A lot of people are using the Dell 2405. The hard part is previewing HDV from the timeline, from what I understand the APVe does not work with Vegas – you can’t use the HDTV component out, it’s a proprietary Matrox driver thing. The decklink is supposed to be awesome for preview but not really cheap – especially if your only working in HDV and don’t need the SDI…
Right now I’m working on an experiment using SLI & two vid cards with Vegas preview to second monitor function. I’ll try and report back how it goes.