Thank you for your quick answers. Pretty much what I was suspecting.
However, with new PSU's running at at least 3-4 times the US price here, and with more than a handful old ones, it was at least worth a shot to see if U guys would think there was a way... Not least because i have all the old ones personally(my own), and my employer are unlikely to finance extras, so I would have to buy from my own pocket or bring the adapter to/from work every day (pain of crawling under the table 2*/day for connecting/disconnecting).
Trouble is - to add insult to injury - that battery life seems to be more like an UPS to just barely give U time enough to save your work while off the AC PSU rather than a real alternative for travelling and working from home.

Oh well- hope I can be allowed to keep my trusted T41P even though its going out of service. Then I also don't have to go from 1440*1050 to <arrgh> 1280*800 - unbearable