How should I connect an instrument mic to my PC?

hey,
wonder if you could help me...I am trying to record myself playing drums.
At the moment, I've got one single mic over my kit with a lead with a mic connection at one end, and a 1/4inch jack at the other end. I then have a little converter from 1/4inch jack to 1/8inch jack going into the 'mic in' port at the back of my PC. (this is on board sound on the motherboard rather than a physical sound card)
I have found the record quality is very poor doing this...is there a better way to connect the mic to the PC?

I have a guitar amp, would it be better to connect the mic to the amp then have the PC connect to the amp's output so that the amp works as a pre-amp? or would that not work?

Or would it be be more worth getting a PCI sound card with a 1/4inch jack port on?

Or perhaps a totally different method to increase record quality?

By the way, my mic is a cheapo instrument mic I picked up for about £20 so part of the problem is probably that.

Cheers,
Tom