Will it be possible that, after the free trial, you'll buy in? Get the one you'd be likely to buy, of course. On the trial, they give you 45 uses (no more) and then you have to give them money.
We THOUGHT we could get away with Home and ran it on trial, and ended up BUYing Pro, and it proved a bit awkward to install. We had to, in fact, uninstall Home and re-install Pro. (Of course, maybe that was ALL MY FAULT!)
Go to the MS Office "home page" and compare features, and judge carefully!
Oh, and, in my opinion some years later, DO consider OpenOffice. It's free, and it fits the bill.