Interesting. Perhaps this may help?
http://sewelldirect.com/Atlona-AT-HDVie ... verter.asp
I found this poking around the Net a little bit ago. It's a device that'll convert a VGA signal directly to HDMI. It's a bit expensive at $100USD, but you could try that. It will also output audio through HDMI, as long as you attach the headphone cable to the output jack on the T400.
Another way may be to get a dock and a DVI to HDMI cable, though you lose the ability to go audio out.
Edit: The page on the device states that it only supports North American HDTVs. However, I know for a fact that a friend of mine was able to connect and play his UK PS3 through my HDTV with no problems whatsoever, but it wasn't able to play through a regular standard def US TV. Strange...

ThinkPads:T21(retired), X200(retired), T500(busted) T400(retiring), T430(upcoming)
Other: Dell Precision M6700(desk hog)