usb-creator.exe did not allow any options other than start and cancel - no reserved space option. It ran on auto-pilot and self-created 600MB of reserved space (if I'm reading the list of post-install files correctly).Download 10.04.3 LTS
Extract usb-creator.exe from the iso.
Run usb-creator.exe in Win 7.
Select Max Reserved Extra Space, (Persistence).
I tried pendrive's universal usb installer, which gave me the reserve option - so I maxed it out at 4GB. I plan to use this pendrive-generated USB to test drive and eventually install 10.04 on the new EeePC 1015PX.
These two different usb makers created only slightly different files on the usb drive - no radical difference that I can tell. But I can post or email a list of both for comparison if someone with more experience (than me) thinks that's worthwhile before I take the 10.04 pendrive USB for test drive on the new 1015PX.
Thanks again for the guidance.