If I am not totally wrong, the behaviour is not due to IsNumeric itself, but to the fact that you can cast this value to money or smallmoney.
Try this:
SET NOCOUNT ON
SELECT CONVERT(money ,'1,0.2') A, CONVERT(money ,'1.0,2') B, CONVERT(money ,'1,100,00.2') C
[font="Courier New"]A.......B......C..........
10.20001.0200110000.2000
[/font]
Now dont ask me why...
Best Regards,
Chris Büttner