fopen gives me a permission denied error

[serevinus]

This line
$fp = fopen("logs.php", "a");
gives me the following error
Warning: fopen("logs.php","a") - Permission denied in c:\inetpub\wwwroot\bc\BC.php on line 279
PHP Warning: fopen("logs.php","a") - Permission denied in c:\inetpub\wwwroot\bc\BC.php on line 279

I am running IIS 5.1 on Windows XP and as far as I know there is no CHMOD command... the file in question is set to Read and Write using the properties sheet in IIS options.
I think it might be somthing to do with user access, anonymous login account is IUSR_COMPUTERNAME but I dont know what option I should be changing (if thats the problem) also I only want to change the access to that file and not to the whole site (I dont really want to give write access to every file in the directory)

Thanks
Serevinus

[Anon]

i dunno about XP meself- but I understand that M$ introduced a hierarchical file permissions structure like we have in linux .. check what user name is starting up the apache server on your box and then check that the folder your html docs are has granted write perms for that user ...