Apple’s second generation iPad goes on sale tomorrow, and the price of the original iPad has already dropped. Furthermore, loads of people are selling their original iPads on eBay, in the hopes of raising funds for an iPad 2. While cheap first generation iPads might look like a great deal, you’ve got to ask yourself: Just how long is Apple going to support the original iPad?

As a company, Apple infamously “outdates” its own iDevices. For example, the original iPhone (the “iPhone 2G”) had a lifespan of around two to three years, until iOS 4 was released. Because the original iPhone doesn’t support iOS 4, it could not benefit from any new features of the iOS, and was stuck at iOS 3.1.3.

However, the iPhone 3G – which was released a year after the original iPhone – didn’t benefit from iOS 4 all that much. In fact, it slowed the iPhone 3G down quite a bit. Apple did fix this issue with iOS 4.2. Now, Apple has stopped supporting the iPhone 3G, like the original iPhone, it too is “outdated.”

So, the question remains: How long does the original iPad have? If we look at the iPad 2, we can see that obvious, hardware related aspects of the new device – such as a couple of cameras – mean there will be certain iPad apps, like FaceTime, that cannot run on the original iPad. Furthermore, high end applications that require a lot of processing power, like iMovie, will not be supported by the first generation iPad (though GarageBand is).

However, apps aside, what many of us care about is the iOS – specifically, how long will it be until the original iPad is incompatible with the latest version of the iOS?

Let’s look back in time at Apple’s past iDevices:

Original iPhone (“iPhone 2G”) – released June, 2007 – outdated June, 2010. Lifespan: three years.

iPhone 3G – released June, 2008 – outdated March, 2011. Lifespan: just under three years.

iPhone 3GS – released June, 2009 – predicted to be outdated June, 2011 (with the release of iOS 5). Lifespan: three years.

As you can see, it generally takes Apple around three years to make an iDevice outdated when it comes to the iOS. If we apply this to the first generation iPad, you can expect the tablet to be supported by the iOS up until June 2013. The original iPad will most likely run iOS 5 and iOS 6 – but, don’t go getting your hopes up for iOS 7, because if iDevice history is anything to go by, the iPad won’t run it.

So, the bottom line is: If you can grab a first generation iPad for a sweet price, go for it – so long as you’re aware that in a couple of years, it’ll be as outdated as the original iPhone is right now. If you’re planning on buying an original iPad, let us know in the comments.