Are those files for this website on the computer that will be running the new OS? Were these files created on this computer with DMX? Were you operating out of a site defined in DMX when you created the files originally? If all of these are "YES" then when you install the new version of DW, it will find the old sites you have on this computer and add them to its list of sites. Then, when you start the new DW, you will be able to immediately select one of these sites (assuming you have more than one) and begin editing the files within that local site. In addition, your Remote site connection information will also be migrated forward, so you shouldn't have to re-enter that.
WARNING - the new DW is VERY VERY different from the antique version you were running (as is the web itself). Methods, approaches, and skills have changed significantly since DMX was released. Further, the new DW will 'expect' you to bring a fair amount of familiarity with HTML and CSS to the table. Without that familiarity, you will experience quite a struggle....
