uninstall/re-istal

I have many problems with my blog
I need to compleely ninstall everything and re-insall wordpress
The sidebars in dashboard show t2 sidebars for widgets when thesis is set to content and one sidebar
Plus I cannot move any wigets by dragging to anything.
The whole thing is messed up somewhere

I wish to do a complete uninstall of wordpress + BASCKUP MY MANY POSTS
Then re-install new wordpress and add my backed up database to it

How do I achieve this as I do not wish to loose two years work.
Fantastico doesn`t work .It says I am on wp 2.8 when my dashboard says wp3.1

Anyone know how to uninstall/re-install and keep all my posts for the new install.?

I have been 2 weeks trying to work it out as it seems to be extremely difficult!

I really would be grateful to hear from some one who really knows how to do this

griffin63