Extra files appear on USB stick

[Hollywood1958]

When copying a single pdf file from Apple G4 via USB stick I get 4 icons (Only when inserted into PC) the original file. A file the same with a dot & underscore before it. A file named
.DS_Store and a folder called .Trashes

 

[Giaguara]

Those files contain the resource forks - you can safely ignore them.
http://lowendmac.com/crews/06/0104.html
http://en.wikipedia.org/wiki/Resource_fork

But you could also try these
http://zeroonetwenty.com/blueharvest/
Prevent .DS_Store file creation on network volumes http://support.apple.com/kb/HT1629