Free Software to help Practice

These are two S/W that I use now and wished I had back in the early 90s. Plus, they're free.

1. Audacity - I can load MP3 and slow down the songs and maybe even remove the vocals. I can also lay down a rhythm track and play lead over it.

2. Powertabs - It's like karaoke guitar tabs. You can change the speed of the song and remove extra guitar parts if multiple tracks exist. Of couse, you need to find the powertabs for the songs you want.