I know how to do that in SQL Server so I am sure it would be similar possible to do in ASP:
To convert the actual date into Farsi (Hope is the same as Hijri)
SELECT CONVERT(nchar, GETDATE(), 131)
To convert from Hijri to Gregorian Calendar:
SELECT CONVERT(datetime, ' 7/05/1421 12:14:35:727PM', 131)
The clue is the 131 thus you have to options:
130 - Returns the date via the Hijri calendar, in dd mon yyyy hh:mi:ss:mmmAM format.
131 - Returns the date via the Hijri calendar, in dd/mm/yy hh:mi:ss:mmmAM format.