Forums Scripts & Popups mirc font

http://img232.imageshack.us/my.php?image=59801724.png

is there a way to correct this? above picture is using Arial font
and the second picture is using Courier New.

That is not Arial.

If you want to line text up reliably then you're going to be limited to using fixed-width fonts. Courier New, Fixedsys and Lucida Console are examples of such. Additionally, some fixed-width fonts maintain the same width with both bolded and unbolded text while others do not.

arr meaning?

It's nothing you can "fix" with a script - you'd have to use a non-proportional aka monospaced font to get the alignment.
If it's a custom window you may use tab stops instead of spaces, and you may play arround with picture windows (/drawtext command).