DVD RB usually has a 6 channel and a 2 channel, should i keep both? I usually watch on hd TV wiht surrond sound and with a syn. hd 555 headphones wiht a creative 2 zs sound card. So would just keeping the 6 channel be good for both laptop use and hd tv use?
Yes. Keep the 6 channel audio. Just be sure it is not the DTS audio track. If you do not have DTS equipment, then you will get no audio if the DTS track is the only one that you selected! With the Dolby Digital 5.1 (6 channel), you will get surround sound, and it gets down-mixed to 2 channel if you do not have surround equipment. 2 channel, well, it speaks for itself...
Teflonmyk is right, leave off the DTS (unless of course you have equipement to enjoy it and want it). I have my system set to exclude DTS automatically in Settings. The 2 channel is almost insignificant when it comes to overall compression. Set to delete DTS and foreign language Audio and subtitles, my backups have always done well with the full disc backup.