First of all, STOP! Make the best purchase of your life ($15) and join the
Timeshare Users Group . Read the TUG board for 6 months before buying ANYTHING.
In my opinion, DVC is a great option if staying on grounds is important to you. I pulled out of my DVC purchase almost a year ago and purchased a Southern California summer beach week ($2500 with m/f of $280) and a South Africa timeshare ($400 with m/f of $130). In retrospect, I wish I would have bought DVC AND these other timeshares. It is virtually impossible to exchange into DVC with other timeshares, so if being on grounds is important to you, then DVC is the way to go.
If you don't mind staying off site (experience this before you say "yes"), then you can purchase other timeshares much cheaper that will trade into exceptional properties in the area surrounding WDW. WARNING: YOU WILL HAVE TO LEAVE DISNEY EVERY NIGHT!!!
If you decide to purchase off site, I would strongly recommend against buying in Orlando. With the exception of DVC and perhaps a few other prized weeks, Orlando is a notoriously poor trader because of the enormous number of high quality timeshares in the area. As a result, weeks as cheap as a South Africa week can routinely change into many of the best non-DVC resorts in the area. In addition, some major exchange companies put restrictions on trading back into Orlando if you own there.
Finally, NEVER buy from the dealer (lone exception: DVC). The resale market will virtually always save you 50-70% off the developer price. Go see TUG for more information! It will save you thousands!!