secure IUSR account

[thompom]

Hi,

Just upgraded from 2003 to 2008 (iis6 to 7) and have given some folders write permission for the IUSR account.
I have some asp apps that write using ADODB.Stream.
How secure is this?
can anyone write files to these folders now?
Are there any steps I can take to improve security?

I ask this question because I had the same setup on server 2003 and files were written (maliciously) to the folders that had write permission for the old IUSER_machine account

thanks MG