New to SM Office and I'm confronted with a similar problem
Originally worked with Excel till it couldn't handle the sheer size of my main spreadsheet and regularly crashed. So I changed to OpenOffice, which really worked that much better. However, with each update it became more resources demanding and, especially working alongside with FF, both increasingly crashed too on my merely 760 ram machine.
Therefore, I'm really happy I found something as fast, sleek and stable as SM Office available, additionally working very well on USB. Where OO or Libre is just too much of Suite to still be responsive and usable especially in Internet shops of poorer countries with slower machines too. (hopefully, SMs fastness doesn't disappear too soon, by such feature request as mine here

However, now I'm confronted with PlanMakers limitation to 256 columns! - My main spreadsheet, where so much work went into, now uses 372 columns and 911 rows in one sheet. With OO I wasn't even aware such limitations exist, until I tried to export it to .xls for using it in PM, when everything beyond 256 columns got cut off.

Therefore, is there any way to have more than 256 columns with PlanMaker 2010?
The only other option to still be able to work with my main spreadsheet seems very complicated compared to how I'm used to work with it now, and work-intense to convert. I would have to cut and paste not so essential stuff to other sheets and this way limit it at least in one direction to the available 256 columns (and run now simple one row calculations across different sheets).
Still would have to transpose the whole thing first, for which PM even would have a button. But really would be needed for OpenOffice (which doesn't seem to have this ability, or I haven't found it yet..) before it cuts off to much by converting it to the only format available in Calc that PM can handle too.
So thought about an other option to convert the sheet to html first, than transpose it with something as a javascript bookmarklet in Firefox (while having it crippled and striped off all extensive formatting..) for being able to start working with it in PM. Building it from scratch does seem too different to this option.
Would appreciate any hind to avoid such a complicated and work-intense conversion, where I probably continue instead with a slow responding OpenOffice and avoid the regular crashes as much as possible by running it without Firefox at the same time. (Actually, that's the status quo: whenever I need my sheet alongside the browser, I export it to .xls and have it open with PM..)