Use of second cd for install?

I was just wondering if this was supposed to happen..
I put in my first GW cd and the installation screen came up and everything. Then when it said to insert the second cd i did, and then it loaded abit and froze. So i had to restart my computer, and when i put in the first cd (I thought i would have to reinstall everything from disc 1 again) It asked if i wanted to play the game instead of installing it, so i did and everything worked fine. I've been playing for about 2 weeks and everything is fine (except i lag horribly sometimes.) I was just wondering if i was actually supposed to install anything from the second disc. And if i should repair my installation. If it has me deleting my maps or anything though please mention it, because i would have to think about it before i go and redownload the maps again, because i'm on 56k and things arent exactly fast.

One enough of the client is install it can stream on demand.

The 2nd cd contained a bunch of data files (objects, maps, etc). If you re-install, it just means you will get all of the data files on your hard drive, instead of having to download them from the server when you need them.

Since your on-dial, put in the 1st cd and do an repair. It should add all the missing stuff from disc 2 that you do have and make sure you don't have corrupted files.