Usually the setting is like this:
Western: proportional: serif 16 (serif: serif; sans-serif: sans-serif; monospace: monospace 14; minimum font size: 12)
Simplified Chinese: proportional: sans-serif 16 (serif: serif; sans-serif: sans-serif; monospace: monospace 14; minimus font size: 12)
The problem is when browsing english web pages containing chinese, like email, chinese font according to “serif 16” and “serif: serif” actually is shown as KaiTi, which usually is not clear when minimum size is set to 12. If you set the western proportional as sans-serif, for english web pages chinese looks ok (SongTi) but english ugly (arial or other sans-serif font). Especially the search column of the Yahoo homepage deforms.
Here is the trick. Set the western proportional as sans-serif but with the sans-serif item set as Times New Roman, which is actually the serif font. Sure the serif item should also be set as Times New Roman. To install Times New Roman font, use webcore-fonts and webcore-fonts-vista rpm package. Then everything looks just like in IE. Enjoy 🙂