Regional font problem

[bobsrkr]

The font that windows uses to display the regional characters of bangla, are pathetically small. I want to change the font that windows uses to display these characters, and I have several better truetype unicode fonts on my system. I have tried changing the font mapping from the font that windows uses (Vrinda) to some other font by-

HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts\Vrinda (TrueType)= Sagar.ttf

But upon system restart, windows just skips the font all together, and uses the bold version of Vrinda. Changing that too, it makes bangla display with boxes! If I try to delete the Vrinda.ttf, windows tells me that it is a protected system font! Please help.

This problem is present in vista, too.