Check out Sonic eDVD. It allows you to add an additional layer of interactivity to your DVDs. Not only can you add links to the web, you can link to other "non'DVD" tyoe contact like excel spreadsheets, pdf files, hi-res images etc.
If i put your DVD in my drive and it opened up a website automatically, especially in a browser window that's already open showing a page i want to see, i'd be tempted to take your DVD out of the drive and smash it to bits, and never obtain another DVD from you ever again.
Interactivity is good. Special DVD features are good. But ONLY when the viewer knowingly wishes it. After all, isn't that what interactivity is all about?