There is no such thing as uncompressed DV or DVCAM, as Vera pointed out.
The Decklink cards are great, work fine (I have one) and are an incredible steal for an uncompressed SDI capture hardware. However, you will need a source deck or converter that can output SDI. This SDI VTR/hardware is far more expensive.
The best use of these sub $300 cards is the broadcast monitor output ability while working in After Effects or Premiere. But then, you need a broadcast monitor that supports SDI input, and once again, it gets very expensive again. Unless you are in a post house, this card is not practical.
If you are shooting DVCAM or DV then I highly suggest you continue using firewire. That will maintain your native signal. While there are advantages to uncompressed SDI in multigenerational compositing, there is minimal improvement, and I don’t see that as practical given your budget. You can achieve the same results by using AE to convert the DV to Uncompressed and work with that.
If you feel like spending some money then I suggest you get the Decklink SP card for $595. This allows you to go component analog in and OUT with XLR audio and RS-422. You may never hook a deck up to this card for capture, but the external monitoring if priceless. With this card you will be able to hook up the component video output to any affordable broadcast monitor for viewing your AE projects and Premiere timelines (render required for DV footage) on a REAL interlaced monitor. This is crucial to any REAL editing or design work.
While you may pay more for the card, you will save thousands on the monitor since you don’t need SDI. Sony has 14″ PVM-14L2 Professional Monitor for $1040 on bhphoto. It even has the important 16:9 aspect ratio switch and of course, component video inputs.