How can I transfer videocassettes 8mm to dvds using the computer ( XP) without losing much of the quality?

I have a PC that has vista installed on it, it does not boot up but just shuts down when it reaches the windows screen. I want to install windows 7 on it to rid the problem but i do not want to lose my files. Is there any way of doing this?

I have xp. Thinking about upgrading to 7 but haven’t found a good way to transfer or preserve files and game saves to the new OS. Is Microsoft looking into it, is there a way to go to vista then to 7? Anything?