2000 Buick Century Re-programming Keyless entry fob

Started my car this morning. Left it in the driveway to warm up. THEN SOME ONE TOOK IT!!! I know. I know. Why did I leave it unlocked? Called the police. They found it within an hour. My problem now is that they have all of my keys. I can replace my doorknobs on the house really easily.....But the keyless entry has me worried. I Reprogrammed the fob using the proceedure for 1999 Century. It went through the steps (made the right sounds at the right time). Everything went just like it was supposed to. Now I read a post that says that I have to have a scan tool to reprogram. Has anyone tried reprogramming their keyless remote? And...... Did it actually reprogam (Like a new security code) the remote? Or does it put the program back on the remote...............Anyone have a clue?

Did you follow THIS PROCEDURE (http://www.automotiveforums.com/vbulletin/showthread.php?t=118680) for programming the remote? If so, does it work? If it does, the old remotes will not work on your car now, but the keys will!

I used the procedure that was given by an AF moderator named "Flatrater". It looks like the same thing. He was giving this information out on another thread. He posted it on (7-14-2003). Like I said..... Everything seemed to work. The right number of "dings" at the right time. But then again the fob worked just fine before. I'm just worried that someone might come back, hit the button on the old fob, and get right in. Now I have to find out how hard it will be to replaced the key cylinder. I sure that it's not as simple as the one on my Caravan. That was a 15 minute job!........ Thanks for the feedback.

Once you reprogram the transmitter, the memory erases and the non-programmed transmitters will not be compatible with the new settings! Don’t worry about this part, just change the door/trunk locks & ignition. You may want to call a Locksmith to see how much they would charge to change the tumblers in all of them. Insurance may cover this modification if you have comprehensive coverage.

Thankfully, I didn't have my door key on that key ring. So I won't have to replace the locks in the doors. The only thing I did right!
Thanks again