I've recorded many songs on my PC. What I did, was buy an adapter, as mentioned in the post above, and plugged it into my soundcard.

I am using a digitech effects board so I just run my cable from the output to the soundcard and my input to my guitar.

The program I use to record is called Magix Music Studio 7. It's awesome. It gives you up to 32 tracks to record on allowing you to layer mask (recording a part and then copying twice to make it sound even heavier) the program comes with a mixer and thousands of options to fine tune the sound exactly how you want it. You can switch speakers causing it to fade from left to right just to name a few cool things. It's really worth the $70 I paid for it. You can buy it at any major electronics store. I believe I got mine from best buy.

You can pick up the adapters from Wal-Mart or any place that has electronic stuff. For my drum beats I use Fruity Loops.

Hope this helps.