The first step to making sure your code will still run after upgrading is to download the Custom Code Validation Tool. This page contains a link to the validation tool at the bottom of the page, as well as detailed instructions on importing the tool into your CRM 2011 organization.
If you follow the instructions mentioned above, you will find yourself looking at a screen similar to this:
The second potential issue is the use of the Disabled property. This property is defined in an .htc file, which is an HTML Component file. These files only work in Internet Explorer, which means they will be going away in the Q4 2012 Service Update. Since .htc files won't be around anymore, the Disabled property will need to be replaced as well.
So how do we update this code? If we take a look at the "Form Scripting Quick Reference" section in the Dynamice CRM SDK, there are two methods named Xrm.Page.getControl and setDisabled. We can use these two methods to update the code to:
Because we are now going through the supported 2011 Xrm methods, this code is guaranteed to work in all supported browsers.