I wanna to recommend an Unicode font type, Wen Quan Yi (文泉驛黑體), for the firefox's default font. It supports Linux, Windows and Mac and its free (of course). Somehow it doesn't work so well on My Window XP but perfect with Ubuntu. Here are some screen-shots (left hand is Window XP, right hand is Ubuntu):


Google Web Search Page


Blog


Picasa Web Album


Forum


Yahoo Sports (The page was changed so fast that I couldn't get the same page....)
I have tried to tune XP for the same display as Ubuntu but failed. That doesn't bother me a lot because I only use Windows XP just when I have to, like SPSS which only supports for Windows. The only one thing I don't quite happy with Ubuntu is the performance of Firefox3 is so slow. Its really a torture to Ubuntu users when browsing webpages with JAVA or JAVA scripts. It seems because the congenital flaws of JAVA on Linux platforms and there are no software solutions to overcome these defeats. I guess a hardware upgrade should help (and I will).