Hi omslemming, welcome to the site,
The database should be pretty accurate on the type of entertainment system, although the predictions of the actual aircraft you're going to get on a specific flight is only an indication based on historical data since Virgin don't release an operating schedule.
The issue of the different types of equipment has been discussed before, but the bottom line is it comes down to economic reality. Whilst Virgin are doing their best to fit V:Port across the fleet (along with the Upper Class Suite), the cost runs at about £2m per plane for the entertainment system alone. Fitting out an aircraft also takes time, and with a small fleet, it's quite a juggling act to book aircraft in for the refit in between normal maintenance, new route requirements and commercial growth.
The Nova system you're talking about (without Nintendo) was originally intended to be delivered to Alitalia, but Virgin bought the 747s when Alitalia cancelled their order. When the UCS are fitted to those aircraft (anticipated from the end of this year to Spring 2005), those planes will also get V:Port. Unfortunately I know this doesn't make your kids feel any better about it on your flight on 30th June, but at least I hope you'll understand the situation a little better. If Virgin hadn't bought those aircraft, or they had concentrated their efforts on upgrading the existing fleet, the Antigua route may well have never started.
Pix