What I do is, I got this Zoom 505 multieffect pedal. I searched on google for patch settings, and modify it with a little bit of reverb (it removes the "electricish" sound you have when pluging it into the comp)
The Zoom 505 is really cheap, you can get it used for about 50$. Sure you can get a better one if you have more money, but to get something average without spending too much money it's good.
And then, I got a multitrack program, and I record every track. When I'm done, all I have to do is play with the EQ, and I'm done. Always depend on the style you want to get thought.. mine is rock/alternatif.
Oh, and if it sounds bad on your computer's speaker, it's kinda normal ... I used to play with my Denon headphones to get something good. Either way, you'll have to get great speaker. Computer speakers seems to be good for games and stuff, but for music they aren't.