Going from WordPress to WordPress

Hopefully someone can help with this.
I am going to be relocating my WP blog down a directory, from https://www.mypage.com/ to https://www.mypage.com/wp/ for example. I am using the WP version before Mingus, but would also like to upgrade to at least 1.2 when I relocate my blog.
I am a PHP and a mySQL novice. If I delete my current WP blog, reinstall Mingus as mentioned above, and point it at the dbase that is storing all my posts, will they still be there when I link up??? Should I back something up?
Any help/feedback would be great.