Help Choosing Capture/Tuner Card...or Other wise

[drtalk]

I'd like to call upon the experience of those veterans to this site for some assistance. In brief, here is what I'm looking for: I want to be able to record & watch video from my Motorola DCT2500 set top digital cable box (not HD). I also want the ability to send audio/video from my PC back to my TV via s-video and standard RCA for audio. The third concern I have is in regards to video processing ability. What I mean by that is, when I finish a production in Sony Vegas Pro and want to render it to a specified format, do the above mentioned card types handle the processing? Lastly, is there ever a concern about having an adequate power supply?

For reference my PC specs are:

OS: Windows 7 Home Premium (x64)
HP-Pavilion FK575AA-ABA a6658f
System Serial Number: n/a
Enclosure Type: Desktop
2.40 gigahertz Intel Core2 Quad Q6600
64 kilobyte primary memory cache
4096 kilobyte secondary memory cache
Board: PEGATRON CORPORATION Benicia 1.01
Bus Clock: 1066 megahertz
BIOS: American Megatrends Inc. 5.30 09/05/2008
Drives: 640.13 Gigabytes Usable Hard Drive Capacity
433.56 Gigabytes Hard Drive Free Space
Memory Modules: 6134 Megabytes Installed Memory

Slot 'DIMM0' has 2048 MB
Slot 'DIMM1' has 1024 MB
Slot 'DIMM2' has 2048 MB
Slot 'DIMM3' has 1024 MB

Any assistance with this would be appreciated. I find the number of choices available on the internet to be quite over whelming.

[drtalk]

*bump*

[edDV]

#3 No, they just capture and/or encode video.

Usually for a cable box you just capture the S-Video and audio from the box. You don't even need a tuner.

Capture devices are availabel to DV (ideal for Vegas), to MPeg2 (also works) or AVC (less friendly to editing).

The cable box feeds the TV and your PC display card also feeds the TV to an Aux input (S-Video+Audio). If the TV is HD there are better ways to connect.