(You've already used up a good chunk of your 1-gig getting headers. That's why you want to get an unlimited newsserver).
The rar's are like zips. Use Winrar to extract the dvd.
If you happen to get damaged/incomplete rar files, then use the pars (and QuickPar) to repair them.
Look around other pages of that Slyck guide to answer any questions you have left.
You're going to be shocked at how fast you can download things this way.