I am delighted with the portable version. I have been experimenting and wonder if i've found a bug?
When using tables one can get sides of a cell without a hitch. But when one wants to have sides of different thickesses it doesn't seem to do it. Neither for that matter does Abiword. I tried both - then compared with WordPro and Word.
It's probably something with OO itself. The only thing you should compare it to is a local install of OO. If it's the same, it's a bug in OO and should be reported at OpenOffice.org. You can pose this issue at ooforums.org if you wish to discuss OO functionality.
Sometimes, the impossible can become possible, if you're awesome!
I'm not sure about OO.o Writer, but this is possible with AbiWord:
1) Table > Format Table
2) Click on the four border buttons to remove all cell borders (make sure 'selection' is selected in the Apply To dropdown, if you want it to only apply to one cell)
3) Choose a thickness and then select the border(s) to which you want it applied
4) Repeat 3 with a different thickness