pdf editing tool

I know this guy with a tablet pc with some program called sniping tool where he can basically cut and paste any sort of document.

Anyone know of a good pdf editing tool (free) that i can use to write comments on pdf files?

what about a free virus scanner (for the parents)?

thanks guys

Free virus scanner: Panda Soft or AVG
PDF Editing Tool: free, don't know. I have PDF Factory Pro, and I think whren you print to PDF it includes comments from word documents.

download.com has a PDF editing tool, $99 or free trial. Although the free deal adds some stuff to it if you save, but not when your print. Foxit PDF Editor....