I purchased my e750 before May 23, so I tried the other link that takes you to Toshiba's shopping site. They claim there are full program details there on upgrading to 2k3, but I can't find it anywhere.
Well, I just entered 5/23/2003 for my purchase date of my e750 (I think I bought it in March) and the ppcupgrade.com website accepted my serial number and credit card. We'll see what happens...
I called the Norwegian Toshiba support phone asking about the Windows Mobile 2003 upgrade for my E755. They said that it will take some time to get it to Europe because they need to test it over here too... But when it's ready (probably in the end of July) it will be available here: http://www.toshiba-tro.de/