Letter From Employee Showing Gratitude........

Hi All,
I need help from you all.

We are going to process US visa for two of our employees(with their interest). as it will cost about a lakh for a single employee, we would like to get a letter from them (not an agreement or bond) saying that, they would like to work at onsite and as they know the company is going to make such a big contribution for their visa processing and all, they will stay with us at least till they visit the onsite for once.

Expecting response from all respective members. If anyone can draft a letter for me regarding the same, I will really be grateful to you.
Thank You
San

Thanks Paranjape for your valuable response,
I know the said letter cant be used for any legal works, still if something like the same is there. upon business ethics, it can work know?? Thats all....
Regards,
San

Hi
You wont spend money unless you are certain about returns.It is after all business. Where is gratitude on this.?
Siva