I e-mail a pen pal in Tokyo, but have to use romaji because I don't know of any way to type in kana using my PC. I have Windows XP, Office 2007. Is there any hidden capability, or software I could buy, that would allow me to at least type in kana? My friend says they can select kanji using their PC's over there. Computers are computers, so presumably there should be something I could install here that would do the same. Any ideas?

Windows XP has native support for Japanese built in but it is not installed by default. You the files you will need are on your install disk or you could try downloading it from Microsoft.
http://www.microsoft.com/windows/ie/ie6/downloads/recommended/ime/default.mspx

Here is what I did.
1. Put in the Windows XP install CD.
2. Go to Control Panel.
3. Go to Regional and Language Options.
4. Click on the Advanced Tab.
5. Select Japanese in the drop down box.
6. Make sure everything with Japanese has a check by it.
7. Click apply.

7. Click on the Languages Tab
8. Check "Install files for complex script and right-to-left languages (including Thai)"
9. Click on the Details button.
10. Click on the Settings tab.
11. Click on Add.
12. Select Japanese in the top and bottom drop down boxes.
13. Click the OK button.
14. Click on the Language Bar button.
15. Make sure you have "Show the Language bar on the desktop" checked.
16. Make sure you have "Show additional Language bar icons in the taskbar" checked.
17. Click OK.
18. Click Apply.

You should now have a JP or EN on your taskbar that stand for English and Japanese. You can change the language you are typing in by clicking on those letters.

Note: Click in the area you want to type in first then select the language you want to type in.

(with the microsoft IME), to quick switch from en to jp, you can hit (alt+`), to convert string to katakana, press F7, spacebar converts string to kanji, keep pressing until selection is made, tab auto completes word based on your writings