Went to Walmart and Lowe's today for tools/parts. I bought an excellent fish tape (at Lowes) for about 17$. It's twenty feet long, flat steel, with a flat tapered plastic head. I tried to cut my carpet with a one of those retractable razors, and it did not work out that well. I switched to a good old folding lock blade, slipped the sharp tip about 3-4 inches from with the edge up. I pushed in until I could feel the carpet cut, then I pushed forward smoothly and gently. It cut the carpet very cleanly. I pulled the carpet up from the 'nail/tack strip'.
I had a small cloth handy. The fish tape seemed to have a very light coating of oil. I did not want that under my carpet, so I used the towel to protect my hand and absorb excess oil. I tried to use a stud finder to locate the fish tape, but it did not work for me. I had my daughter watch where the slight bulge in the carpet went until it reached the other side.
I did a neater job of cutting the second side. I found some little plastic tacks (also at Lowes) to hold wire against wood or molding. I used those to secure the wire where it comes out from under the carpet. I also bought some Wiremold(tm) thin plastic self-adhesive conduit (Lowe's). I ran this up to some inexpensive (2 for 8$) speaker wall mounts (WalMart), which are supposed to be good for 10 lbs.
The wall mounts took some jury-rigging, as the wall-mount slots on my SKS-HT520 surround sound speakers are smaller than the screws provided with the speaker mounts. I ran 16 guage speaker wire which I purchased in a 100' roll for about 18$ (WalMart).
I didn't buy them, but WalMart had 6' TosLink cables for about 15$, which was 10$ less than the same cable at Best Buy. They also had a 6' digital/coax cable for about 13$.
The speaker wire is under my carpet, and is totally invisible. Actually, it's under the carpet pad for a good part of the length. I started the fish tape under the carpet, but by the time it reached the other side, it was under the pad. The Wiremold conduit is a very neutral off-white (technically Ivory). It blends very well with the stock off-white paint in our living room. The speaker mounts are very nice for about 4$ apiece. They allow adjustment of speaker angle, and provide a nice professional look to the whole job. We watched Star Wars episodes V and VI. I could hear the Tie Fighters come screaming from left rear to front-center. The explosions and pyrotechnics were awesome. There may be better speakers out there, but my SKS-HT520s coupled with the TX-SR502 make for a mighty fine theater sound.