For Windows users, the Input Method Editor (IME) is one way to type Japanese without using a specialized keyboard for it. However, you would need to have eastern fonts installed on your computer.
Steps for Vista users:
1. Open your 'Control Panel'
2. Open 'Regional and Language Options'
3. Go to 'Keyboards and Languages', click on 'Change keyboards'
4. Under the 'General' tab, click on 'Add'
5. Look for 'Japanese', then make sure the box with 'Microsoft IME' is ticked.
Now you should be able to select Japanese from the language bar.
Edit:
Can any of the moderators please move SufferingLove's thread from the lessons subforum onto the main forum or questions subforum and make it a sticky or announcement? It should help those without eastern fonts know how to get it.