Pre-orders for the Apple iPad have gotten off to a pretty good start. According to sources, Apple was able to take over 51,000 pre-orders in the first two hours of accepting pre-orders. The more impressive number is the 150,000+ iPads that have already been pre-orders since they started taking pre-orders. The initial pre-orders are expected to arrive at Apple stores for an April 3rd pickup. Some analysts are predicting that Apple could rake in over 500,000+ pre-orders before launch and they should be able to easily sell one million units by the second week of release.

While our sources insist that that pre-orders are split among the different configurations, it would appear that most buyers are tending to lean toward the high-end or low-end flash memory configuration. Accessories for the iPad could be in short supply on release day. From the whispers that we are hearing, it is quite possible that retail stores will sell out of iPad accessories on launch day, as well.

As we told you in a story yesterday, Apple has announced a $99 battery exchange program for users having battery problems. We are hearing, however, that Apple is expecting the exchange to take a week and don’t even bother to attempt an exchange if your iPad is damaged or has been modified in any way. And don’t forget that you will need to sync your iPad with iTunes before sending it off, as that will be the only way to get your data on to your new iPad when it arrives.