I'm putting together a booklet for my homebrew game for a playtest group. Who knows, someday it might go on RPGNow. In any case, I want it to look at least reasonably nice and I have started laying it out in Scribus. So you know my tools: I use Open Office exclusively at home. I have access to Photoshop and Illustrator, but not Indesign.

What I am trying to do right now is lay out a list of powers, a la 4e D&D. I would like to begin each entry with a power title overlaying a colored bar. Below that will be a brief 'stat block' and below that will be a description of the power's effects. Followed by the next power entry and so on.

The booklet is sized for 7" X 8.5" pages (Legal sheets stapled and folded in the middle) so I will probably be working with about 4.5" wide columns, one column of powers per page, with a 2" sidebar on each page.

Should I be laying out these powers in Scribus? Is there an easy way to do this (don't forget the colored bar behind each power's title, as well as the non-uniform inches of text in the description)? Should I lay them out in Open Office's word processor or even spreadsheet, then transfer them into Scribus? Or should I set them up in one of my art programs, then paste them as images into Scribus (btw, this seems like the sloppiest, dumbest way, but might actually be the easiest)?

Any advice for me?

You should be able to group the necessary elements of the block in Scribus (appropriately named) then copy-paste the block template easily.  So long as you have all of the powers information prepared, it should be easy enough.