Welcome aboard, Aequitasx.
If you have dynamic mics (i.e they don't need batteries or phantom power) then you can probably just go to radio shack and drop about $20 on a couple cables and adapteres that would do the trick. The salesman can help you find what you need. Take your mic with you just to be sure, unless you're confident you know what you need.
Be warned that it won't sound all that great- the preamps in the computer probably aren't going to be all that pleasant. That's why Farview pointed you to M-Audio products. They replace the soundcard with *much* better preamps- less noise, better sound, better all around.
When I first got serious about computer recording I tried pluggning the mic into the computer... lasted about 2 days before i bought a Tascam US-428. Plugging straight in got me hooked on the computer, but... oh, it sounds bad.
Take care,
Chris