Thinking of going SPDIF need advise/reassurance.

I currently use a SB Live 5.1 connected to an Analog 5.1 Receiver. My PC is also connected to a 27" TV and I use it to play DVDs, CD, MP3's DivX with AC3 ect.

Howver I can't get the subwoofer channel to work because the subwoofer channel requires a 4 pole to 3 rca cable which no one seems to make. Apparently there are similar cables for Digital Camcorders and Macs but the pin out is different!)

I am thinking about getting a $300-$400 Digital Receiver (Pioneer VSX-D912) with optical and coax digital inputs. I would also rather use the optical out on my cheap integrated CMedia sound card and move the SB to my other PC if possible.

If necessary I am willing to invest in a new sound card if for some reason the both the Cmedia and SB live lie about digital 5.1 support.

Here are my questions/concerns.

1) Any chance of me spending $400 for mid range digital reciever and simply have it not work well with my PC?

2)Can I get away with using a CMedia card since it will be using SPDIF pass through rather than decoding?

(If anyone actually uses the digital out on a CMedia card please let me know if your experience was in any way problematic)

3) Will I have any problem using AC3 filter (version 70b) to watch DivX's with AC3 audio streams? The filter works fine with my SB when decoding but I have never used it for pass through nor could I test the subwoofer due to the connectivity problem.

(The docs says it supports AC3 pass through, but I would rather have confrimation form someone who uses this feature before investing in a reciever.)

4) Does anyone know of someone who actually managed to get the SB Live 5.1 analog subwoofer channel to work with a 5.1 reciever or any non SB 5.1 speaker setup?

I can't afford to buy the Pioneer VSX D912 if I purchase it locally, buy if I save $100 by getting it on ebay I will not be able to return it. So any input is greatly appreciated!!