I have used an excel logbook in two different interviews and it's never been an issue. As long as it looks presentable you should have no problem.

I printed out my "logbook" on good quality 8.5 x 11 paper in color laser. At the bottom of each page in the footer I printed out a signature line/box for me to date and sign along with the text verifying all entries are true (whatever the common text for a logbook is... I don't have it in front of me).

Once printed out, I simply slid the pages into plastic sheet covers and put them into a high end (read very nice looking professional presentation) 3 ring binder. This way as I add more pages to my logbook, I don't have to go to kinkos to have everything reprinted/bound.