and if a PDA is too small (and I agree that it is), you're left with only one real option. You can get a pretty small laptop if you really can't face carrying a conventional-sized one, but be prepared for a serious pain in the wallet for the smallest ones. The absolutely gorgeous Sony VAIO VGN-UX has a 4.5 inch screen, but runs Windows XP professional, and is a fully-fledged PC. The downside is that the version with 1Gb of RAM will set you back to the tune of £1800 or thereabouts.
Alternatively, for less than half that cost there's a nifty little 12.1 inch screen-sized laptop from Toshiba click here that comes in at around £750