I’ve been meaning to blog about this one for a while, but here it is: the TARDIS PC.
More images and a write-up here and here (and, I daresay, all over the web). Annoyingly I upgraded my PC not long before I got sent this, and to the best of my knowledge it’s not currently being sold as case only.
Of course, it’s not the first time someone has used Doctor Who to flog a personal computer…
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Brian of Morbius 
They were good. Prime computers are so futuristic-looking… I’m amazed they were able to use so much BBC-owned stuff, though. I even recognised some of Lalla Ward’s costumes! According to Wikipedia Prime was defunct in 1998. It also says that these adverts were included on the Destiny of the Daleks DVD which perhaps accounts for their good quality.
Tom Baker did some other Who ads (in New Zealand I think) that I saw once. I’m not sure this is what I’m thinking of, but it might be: