New Mic vs New Soundcard

So here's the deal: The soundcard on this PC crapped out. It's a mediocre laptop that has enough processing power for me to do the things I need to do, but the Line In & Mic In jacks on the soundcard have this wierd problem. Everything comes in at a very VERY quiet level , so quiet that when I amplify the sound it has a noticable level of fuzz on it. It just started doing that one day (so I know something went wrong, it wasn't always like that). The audio out jack sounds perfectly fine though. I don't really use the line in for any instruments. My guitarist records on a different computer. I only really use it for the microphone, to record vocals or random home-made percussion to sample.

I'm considering either:

1) Buying a USB microphone to record stuff

2) Buying an external soundcard and using the old microphone

The USB microphone I was looking at is this: http://www.amazon.com/BLUE-MICROPHONES-Mic...p;s=electronics

I don't have anything specific in mind for the sound card.

My questions for you WATMM, are:

-Is it a better idea to just buy a new soundcard and use the old mic? (I have a fairly old Shure microphone from the 70's I inherited from my dad, but the sound quality is still ace. It's got antique asthetic value as well)

-If anyone knows anything about that microphone, what can you tell me about it?

-If you suggest getting a new soundcard, what do you recommend under $150? I'm not looking for a be-all end-all piece of hardware, just something that will get the job done.

Thanks!