I don't believe it is an 'older issue' - it is a current issue for me and should be for anyone considering a cms. Joomla has changed the way it releases new versions and there is no reason to install 1.5x now unless you are committed to using one of the extensions that are not yet compatible with 1.7 such as some of the shopping carts.
If it is a new installation then 1.7 is the go, then a one click upgrade to 1.8 in January. All future upgrades will be one click only.
As migrating from 1.5 to anything higher is problematic, the one click install for 1.5 should, in my opinion, be removed and replaced by 1.7 asap.
As for a manual install of 1.7 on DH the documentation is available at: http://docs.joomla.org/Installing_Joomla!_1.7
Informed discussion of the upgrade path for Joomla is to be found at: http://community.joomla.org/blogs/community/1470-need-to-know-17.html