Risk of Viruses Found

I currently picked up several viruses on the Norton scan as follows. I have a few files which are pretty important so my only concern is that they may have been compromised. I have backed up the files on a usb stick but still don't want them to fall into anyone elses hands. I try not to download much and am very careful of the source when I do. They are quarantined. How much are my files at risk at the moment if any at all? Could my files have been read? How do you think I picked up these viruses in the first place? Help is appreciated. Thanks. 

 

fa8f07a-775dced5.

vmain.class

31bba1f4-4c09453c

vmain.class

1eff1eb-24601b79

vmain.class

7bfdfd8e-4456983d

AppleT.class