Yep thats about it.

Me, I started with an SM57 straight into a Tascam 424 mk III (not as posh as a computer) and at the time I thought it sounded great.

An SM57 will set you back about 100 USD.
The cable may be a little expensive (XLR to XLR)
Get a second hand Behringer pre (40-60 USD)
a cable from your Pre to your sound card.

You are good for guitar and vox.

I'd also STRONGLY suggest some form of compression and mixing through flat response near field speakers rather than headphones however that is another story for another day.