need help about choosing equipments

[darkclaw3000]

ok so im just gonna cut it short..
im a total newbie at all this..
im gonna do alot of recording over tracks..

in other words, KAROAKE. that's just the simplest way to put it..
i got the track without vocals, and im supposed to fill in the vox.

im gonna use my pc for all this..
so what equipments should i get..?
i currently have a mic already.. a Shure SM58. (used it mainly for singing in jamming studios actually, nvr for recording on pc)

what other stuffs should i get?
and can i have opinions about which should i have?
hopefully cheap but good.
i prioratize on 'good' then cheap.. not too expensive pls hehe..

thanks guys..