Using imaging software with Viste Enterprise

Can anyone tell me how to successfully create an image of a Vista machine and then deploy it to other machines? I have a volume license so that is not an issue. I have created an image using Altiris Imaging Software successfully, however, every time I push that image to a new machine, or even the same machine, the boot manager comes on asking for install disk because of hardware changes. The hardware is "identical", all machines are DELL755s with the same equipment.

Thanks for any help