Sure, but the ISP has nothing to do with the support of PHP. It is the provider of your internet (comcast, bellsouth, ect) and stands for Internet Service Provider. I think you meant your host.
1) You need a space between form and method.
2) That enctype is only used for sending uploaded files. Remove it and that script should work.
Code:
<form method="post" name=form onsubmit="return validateSend()" action="http://xxxxxxx.x10hosting.com/sendform.php">
Also, this is a programming help issue. Technically, yes it is a third party script, but this thread is mostly reserved for wordpress and SMF type scripts