yes you will loose your data. if you do buy a new mobo i would reinstall anyway. if you have a burner just backup. there are many new boards avail that are good. if i were to buy something new i would go with the Asus a7v333 or the shuttle ak35gtr v2.2 (the kt333 version) the nice thing about the shuttle it allows for up to 2.30vcore. Note one thing though its only the v2.2 that is the kt333 chipset the v2.1 is kt266a. I would go with the shuttle for the vcore unless you want to mod the v chip.
here's the shuttle review
http://www.vr-zone.com/reviews/Shuttle/AK35GTRv22/
here's the asus review.
http://www.socketa.com