Between a turntable and your sound card you need a phono preamp. That is a device that changes the equalization curve from that recorded on vinyl back to flat. here is a description of what a phono preamp does:
http://www.fact-index.com/r/ri/riaa_equalization.htmlIf you have a reciever with a phono input, you can plug your turntable into the phono input of your reciever and then use a RCA to miniplug adapter to run from the tape out of your reciever to the input of your sound card. (assuming your laptop sound inputs are miniplug). You don't want the mic input on your laptop, use the line input port.
You don't need a reciever if you have a standalone phono preamp. Thats what I have. Run this straight into your soundcard line level input.
If you have sound processing software that has an RIAA filter built in, you can go directly to your laptop line input using a RCA female to miniplug adapter. After you have captured the WAV file from vinyl, apply the filter and you'll be ready to make MP3s, or whatever an ipod takes.
I've been listening to Thick As A Brick lately on vinyl.
EDIT: I found this
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=970-1018. I use something else, but this is a cheap fix and you can get your RCA->mini cable there and is probably good enough for what you are doing.