Decisions in Orlando are tough, especially if you only have a week! All the theme parks in Orlando are good (although I have my doubts about Sea World!) so whatever you choose you will be a wonderful time. The best think to do is decide what type of theme park attractions you would like to see, and then tailor your week around that. It will not be possible to see everything in a week, so priorities will have to be made. Buying the Brit's Guide to Orlando, as others have suggested, will help you get the most out of your time and money. With a week to spend my priorities would be:
Animal Kingdom
Islands of Adventure
Disney Studios
Typhoon Lagoon (water park)
Universal Studios
Epcot
At a push I'd skip the Magic Kingdom (he said, donning his flame-proof suit!), but if this is likely to be your one and only experience of Disney you probably should make the effort to spend some time there. I really didn't enjoy SeaWorld, so we won't visit again regardless of how much time we have available.
Regards
Rob