Specifically what are you having second thoughts about????
The general rule of thumb has been if you go to WDW at least once every other year, and stay in the deluxe resorts that DVC will save you money in the long run.
The only regret that the wife and I had was that we didn't purchase until 1999, and we went at least once if not twice a year to WDW. I know it's a bunch of money that you're commiting to, but all you have to do is look at what Disney's charging for hotel rooms and how they've been increasing in price year after year and it help take the edge off the decision.
If you want to put your mind at ease about DVC, simply begin reading this board. You can search through the archives for topics that you are specifically anxious about, or just read the board in general. As long as you enjoy WDW, enjoy the deluxe accomodations there, and plan on being there as often as you say, you will almost certainly LOVE it... but don't take my word for it, there are a great many people here with up to 10 years more DVC experience than me - Just read the board, and you'll feel better and better about it. If at some point in the future, after you've taken a DVC trip, you decide at that point that it isn't for you, you can always resell it to someone else. So don't worry, you'll be fine. But you won't want to resell it, because you'll LOVE it...
Rob UK: WELCOME HOME...again!! Nope, I don't think you made the wrong decision...but that's something only you can decide. However, if you read these boards like everyone else has suggested, I think you'll realize that you made a great choice. Our only regret was not buying 5 years ago!
My husband and I have been members since 1992 and have never, ever, regretted our decision to join. It was probably (next to getting married and having our children) the best decision we have ever made. We thoroughly enjoy Disney and the DVC!!!