Thanks for replying.
That makes sense about the date. And it looks like I had the latest version after all.
I started my search
on the Intel site, and though they have a driver (which implies the graphics chip can handle 1440x900), it won't install. When I run setup I get a message saying that it won't run on this machine and then aborts - no other options (I can redownload and rerun if you want the exact text).
I also tried using Intel's 'check my system' tool to see what it came up with, with the following result:
Product Detected Mobile Intel® 4 Series Express Chipset Family
Current Driver Installed 7.15.10.1527
A customized computer manufacturer driver is installed on your computer. The Intel Driver Update Utility is not able to update the driver. Installing a generic Intel driver instead of the customized computer manufacturer driver may cause technical issues. Contact your computer manufacturer for the latest driver for your computer.
Which is what brought me to the Toshiba site in the first place.
I'm reluctant to override advice that warns of 'technical issues' (and tbh not quite sure how, short of removing existing drivers so the install doesn't detect them and abort - assuming that's the only things stopping it). If someone has exactly the same model Portege/OS as me and has gone down this route without problem, that would be useful to know. Drivers are such pernickety things!
Thanks
PS - the LCD I've hooked up has PC in and supports 1440x900@75. I can use it as is, just everything is stretched and a bit blurred as a result, and I can't stop it going widescreen on me - the TV isn't that sophisticated!