You might also like to check out
iCalamus DTP program. I understand the only limit with the trial version is that your document is limited to two pages.
I used Calamus, from the same creators, on an Atari ST, but I've done no more than play with this one, so can't vouch for its "serious" usefulness. However, nothing to be lost in downloading and having a look. A letterhead sounds like a good experiment
It also has a
forum where the posts suggest users take it seriously.
QUOTE
iCalamus is the publisher for Mac OS X – light as a feather.
You can use iCalamus for free. The unregistered version offers a lot. If you want to get even more power, for 129.00 EUR (169 USD) you get a powerful modern DTP program which helps you publish your ideas fast and easily.
iCalamus requires Mac OS X v 10.4.5 or later.
NEW: Supporting Leopard, Snow Leopard, Lion!
And, hopefully, Mountain Lion