Software suggestions wanted

I am in need of three software recommendations..

1. something that checks the integrity of the files I'm about to download - a few times I've loaded an nzb into alt.binz, waited for 3GB to download, and the rars either weren't complete or were corrupted.

2. what's the best software to preview video within rar files?

3. Also what tool do you guys use to track monthly bandwidth? comcast has imposed quotas as of last year so I'd like an easy way to track bytes transferred..

thansk!!

1- they are called par files. use them.
http://www.ghacks.net/2007/05/03/par2-files-explained/

2- altbinz has video preview built right into it. if you dont want altbinz, use nzbplayer
http://www.nzbplayer.com/

3- see here: google ftw
http://www.google.com/search?q=track...ient=firefox-a