I am creating a workflow using SharePoint designer 2010 and a need to send to a user a notification email when a new item is created on my list. Is there any away to change the value of a field within the email that the users receive ?
Yes.. It depends what you want to change and how you would like to change and all the configuration regarding that you need to do it in designer workflow itself before framing your notification email.
For example: if User is entering a item with Title as ABC and you would like to show that in the mail as XYZ, first define a workflow variable like Title2 and in the workflow define an if else condition as If Title= ABC set a variable Title2 = XYZ
And when framing workflow email, call Title:[%workflowvariable:Title2%] (syntax is wrong but you will get it once you start creating)