Hi Gorgos,
The difficulty in connecting to MS SQL through PHP varies on which platform your PHP script runs from.
If you're running on a Windows environment, there are no great difficulties, so long as it was set up correctly. Check in the php.ini file that the following is set under [MSSQL]:
extension=php_mssql70.dll
Under Linux/Unix, connecting is a pain in the arse. Take a look at the notes at the PHP site:
http://uk.php.net/manual/en/ref.mssql.php
For more joy.
Regards,
David