I decided to format my PC and reinstall Windows Vista. I did it a few times but before I built my site with VSD. I had a lot of problems in the same situation but with a different software so I want to avoid it this time. Is there any guide on how to save all files, images, form etc and then restore it safely so that the VSD will find all later on?
Thanks.

Do a save as with your site to a flash drive. This will copy most of the needed content. Now publish the site saved on the flash drive to see if VSD can't find some of your files. The other thing you can do is click on "Edit" then "Remove files" and go down that list to make sure you have all the files safely placed on the flash drive. It' doesn't hurt to use an external ftp client to download all the files to a backup folder of go to your cpanel and copy the directory to another for safe keeping.

What about forms on the website?

Flash or html?
If you used the flash tool then VSD should have those files but like I said make sure you have them. If your using the new form builder your probably using an external ftp client to upload the files anyways so the form wont be lost. There again make sure you have all the files. Oh and one other thing, did I mention to make sure you have all the files.

Thanks. I've used the form builder v 1.2 build 3613. I will do it within next couple of days. I will test and retest before I erase my drive. It is a couple of days job.

What I do also is have a folder to keep everything in that you add to your site. That includes any images, forms and documents. Lets say you want to add an image to your page. The image is on your desktop. Copy this image to this dedicated folder for VSD then when you want to add the image to your page browse to the special folder not your desktop. This way you always have the needed files easy to find if something were to happen.

I saved it to the flash drive, published the site from the flash drive and all works fine. Now I noticed my mess with all the site files. Thanks for your help.

Yup been there done that. That's what the dedicated folder will solve. Even if VSD loses the files you can easily find them.