Here are links to the sites of some music programs I use.
Tabit - http://www.tabit.net Tabit is by far my favourite tablature program! The ability to quickly input large ideas, complete with guitars, bass, drums, and vocals makes it easy to save new riffs and ideas, and has been an invaluable songwriting tool for me.
n-Track Studio - http://www.fasoft.com n-Track is a multi-track audio recorder...this effectively turns your computer into a recording console.
yohng.com - http://www.yohng.com This is George Yohng's page. I used his (free!) 4Front Bass and 4Front Piano VSTi and I think they are great! These are what I used to get bass and piano sounds. I also used his (very helpful but not free) mastering bundle.
Absolute Drum Samples - http://www.drums.sk These are the drum samples I used.
Drumsite - http://www.guitar.sk/drums/drums_main.htm I actually used the precursor to this program called Drums! for my drums. The new program Drumsite seems to be much better.