I confess - I was a lazy bastard and didn't use macrons when I wrote the word "romaji" in the eponymous post yesterday. Macrons are those lines above vowels which signify that the vowel sound is long, e.g. ō. They are a feature of the Hepburn system of romanisation and are very handy because doubling up vowels to show elongation results in things like "roomaji" which will screw up your pronunciation up even more than rōmaji already does. So, with a big slice of humble pie I apologise for pointing out the mote in my neighbour's eye when I should have dealt with the plank in my own and I offer my not-so-quick and dirty guide to adding macrons in XP (I am using the office computer).
1. Click the Start menu.
2. Navigate through to the Character Map palette:
Programs->Accessories->System Tools->Character Map
（すべてのプログラム＞アクセサリ＞システムツール＞文字コード表 for Japanese keyboards)
3. Open the Character Map, select the font you are using, or the closest match (this blog uses Lucida Grande but the Character Palette had Lucida Console - close enough!)
4. Select and Copy the character you need.
5. Write a spiffy article, complete with macron enabled rōmaji!