Is it possible to shield unshielded speakers?

Normally, you can unscrew the speakers from the front of the cabinet. I have not tried this, but I wonder if you can reach in and arrange some heavy duty aluminum foil on the side of the cabinet facing the tv. It would probably help if the foil could be sandwiched between the insulation inside the cabinet -- otherwise you might get some noticeable resonanance. This would be a cheap and easy experiment. Another plan of action would be to contact Paradigm to see if they have an aftermarket shield that can be applied to the speakers once you remove them from the box (there are normally four or more screws holding in the speakers -- you probably don't have to worry about the tweeter since that magnet is so small). I've found the customer service at Paradigm to be exceptional. Good luck.

Is the new tv gonna be a tube or projection? If you are going with a projection, you won't have any problems.

I'd wait until I was sure there is a problem.
If the speakers are screwing with your picture, then follow Ozfly's advice and see if you can replace the drivers with shielded ones.
Lastly, you can buy some sheet copper and try to fashion the shield yourself.
Yes, it would look kind of funny.
I wouldn't take this approach.
Good luck!

Aluminum and copper will not do the job for magnetic interference. You need iron or mu-metal. The former is heavy and hard to work with. The latter is expensive.

Since you're planning to upgrade your TV to a widescreen and you stated that your room is small, why not get a plasma, which is widescreen. It solves your small room issue and magnetic shield problem. In addition, it would be a WOW factor and pics would look great. Ready to refinance? :> )