Tell your local RadioShack to get into shape! If you had come into my store, I would have told you that all you need is
a turntable,
a
stereo RCA to 1/8" y-adapter or something similar,
and a lovely piece of free software called
Audacity (the same stuff they package with ION brand USB turntables).
Just plug your y-cable into the RCA outs (I'm assuming your turntable has RCA output here) on your turntable, and plug that 1/8" stereo plug into the line-in on your computer.
Install Audacity, read the instructions thoroughly, and set the program up to record. You'll want to select "Built-in input/line in" as your audio source, and set your recording quality to whatever you desire. (I set mine to 4400 samples/second, but you may want yours lower.)
You'll want to press record on audacity
before setting your needle, you can always chop out the empty space and the sound of the needle setting afterward. After that, just let the track play through, and stop the recording at the end. If you're dealing with gapless tracks (like tracks 3-10 on the b-side of Abbey Road, for instance), just play through all of them and cut them by hand so you can have smooth gapless playback when you play it in iTunes or burn it to a disc
If you fool around with the settings, you can even set the program to record an LP at 45 speed, and knock the audio file back down to standard speed. It saves you time, but it also makes just listening to your collection during recording a little less enjoyable.
Hope that helps (especially on the money side)... feel free to PM me with any questions.