Don't forget some good monitors and a good set of headphones. I use M-Audio BX8 monitors (a little overkill) and Sennheiser HD 280 headphones. A good interface between your gear and your computer is very important as well. I use a PreSonus Firebox, which is basically an external soundcard. Don't forget about mics for recording your guitar (micing your amp or acoustic guitar), and vocals. I use the old standard Shure SM57, but have heard very good things about the Audix i5 mic. I use an MXL condensor mic (cheap) for vocals and acoustic and various other stuff. It's not great, but it gets the job done. As far as software goes, if you get a soundcard that is made for recording (no soundblaster crap), it will usually come with some recording software (typically Cubase LE).