Hi manewman,
As far as I can make out, all Vista DVDs are identical and contain all versions of Vista (with the 32-bit and 64-bit versions being on separate discs). It is the product key that you enter during install that determines which version (and therefore which features are/are not) is installed. The Enterprise product key is aimed at businesses of upto 250 computers and is designed so that the same key can be used on multiple machines of the same type. This is to facilitate ease of deployment by the company's in-house IT support department. As this licensing option is geared towards business operations, this key will install the Business version of Vista. The only way of getting Media Center onto your PC would be a clean install of Ultimate with a new product key (as suggested by Shawn). This would give you all the features of the Business edition, together with the media capabilities that you require. You should be aware though that your IT department may not take very kindly to this and may automatically reinstall the Enterprise (Business) version of Vista on your machine. It is possible to install additional programs that give some, but not all, of the facilities of Media Center, although again your IT department may have put restrictions on your system to prevent the installation of such programs. Even if they haven't, it is quite possible that when they carry out the automatic redeployment of Vista to your machine (as mentioned above) that this restriction may be put in place.
If you are using the Enterprise license on your home PC then you could also be in breach of the licensing terms as this license is only intended for businesses. To be on the safe side, if this is the case, I would purchase a new product key and use that to perform a clean install of the Ultimate version of Vista.
