Wanting to go virtual, meen you want some vsti instruments. They are software you open in your DAW that are samples of real instruments that you can play on your keyboard en record. (you can actually record midi information from the keyboard in your DAW and the play that midi notes in any virtual instruments.) What's nice about it is that you can edit that midi information and remove mistakes add notes or even play at a slower pace to record and change the speed of your project to get it faster. Once recorded, you can export those notes played through a virtual instrument to make an audio file in your project and mix it as if it is a real recording.

I suggest Addictive Drum and Trilian for bass.

For your guitar, you need a good sound card that has an instrument input, you can use an amp simulator software. Guitar RIG and amplitube both make good job for rock/metal.

That way everything is done in your computer.

Of course while virtual instruments and amp simulators are very convincing, you can't replace a vocal. So that sound card need a mic input as well. (with a decent preamp)
And you need to pick a mic that puts your voice at it's best. (not necessary the most expensive) Just go in a store, ask them to let you try the mics starting from the cheapest going up.. Listen how your voice texture change from mic to mic and choose the one matching your budget and your taste!