Easier to change to new theme?

I've worked with FrontPage 2003 for years to put up basic sites, but am now working with WordPress for a CMS site with a blog. Yikes. I downloaded the bytesforall theme and have been struggling with it for days -- can't even get the text wrap around images right yet.

Looking through info more closely, it looks as though it's a fairly old theme. But if I upgrade to Atahualpa or Montezuma, which seem to have more customizeable features, will I lose the days of work I've done with images and graphics on my bytesforall pages?

Thanks!

Meg