Just make sure that you're mindful of battery vs performance.
A 7200 RPM drive will perform better than a 5400 RPM drive, but it will also soak up more juice.
So ask yourself whats most important to you in this device? Performance or battery?
My choice was battery, but 30 Gb was just not enough, so I went for the 40 Gb 5400 RPM version which should allow for solid performance but reasonable battery life too.
Memory uses memory to keep the state in the cells, but this is minimal compared with paging out to the hard drive, so more memory is a better choice than less.
Update: It turns out that Hitachi have been innovating while I'm not looking. They've got a low powered 7200 RPM hard drive that will be in the EO. Frank has the details. See his comments below and here
Other related posts:
Is this my next UMPC?
UMPC's coming to NZ
Local coverage and a Vista TIP tip
Comment by Frank J., on 28-Apr-2006 01:11
Sorry, darryl but you are wrong. Check this link http://ultramobilepc-tips.blogspot.com/2006/04/7200-rpm-less-battery-life-myth.html Hitachi 7200 RPM HDD do not "suck more juice". And I checked with Martin, the 7200 RPM HDD that they are installig on eos are Hitachis.
Comment by Frank J., on 28-Apr-2006 01:18
Here is another page about this topics with tests that proove that 7200 RPM does not mean less battery life. http://forums1.itrc.hp.com/service/forums/bizsupport/questionanswer.do?threadId=675157 So, call them back and change your order, you still have time for that. ;)