Form - Javascript / Jquery On Submit Help

Please give me your best quote for this job.

I have a form text area that I need a script to change the content when the form is submitted.

I need it to detect hyperlinks in the form - written like http://

On submission of the form, the script should detect the links and add the appropriate html code so that the links are clickable.

eg. http://www.bbc.co.uk

a href = the link etc. - this won't come out properly on this job post for some reason.

BUT I ALSO NEED...

To Prepend the href with my own string - href= mystring=http://www.bbc.co.uk

and finally..

I need to encode the url after my string -- so in this example I would encode the bbc.co.uk url.

I have some sample code and will discuss this with someone who can help.

Thanks
Nick