There is not too much you can spoil when trying ISP on a new LPC93x - it comes from the factory set so that you don't need a crystal/oscillator connected (runs from internal RC oscillator by default) and don't even need to do the "three-reset-pulse" trick to kick it into ISP, it's "plug-n'-play", connect only 3V supply and the MAX232-type level convertor... Nevertheless, I would try to run a plain terminal emulator (well, maybe not hypeterminal - my favorites are Terminal by Bray and TeraTerm), type "U" for autobaud and "talk" with the chip using some harmless intelhex records (reads)...

If you have ISP'd it already (maybe even unintentionally, running FlashMagic and clicking here and there), it might be in any state depending on how you set the various flags - which one obviously will not remember... Well I don't know what to do in that case but you might need to use the three-pulse reset as well as trying to connect an external oscillator (better than just a crystal...)

Jan Waclawek