So you're buying an iPad...

With the exception of the original iPhone, it's hard to remember a more anticipated piece of technology in the last few years than the iPad.

If it does follow the same pattern as Apple's iconic smartphone, that implies that the touchscreen tablet is going to do very, very well. Initial reports have listed the number of preorders in the "hundreds of thousands," and tech industry analysts are forecasting that Apple might sell 6 million iPads within a year. That's astounding because, first, that's how many iPhones Apple sold in the first year, and second, because the iPad isn't a must-have device like a phone or a computer. It's a nice-to-have hybrid that's an entirely discretionary kind of purchase.

The iPad goes on sale at 9 a.m. Saturday at Apple Stores and most Best Buy stores in the U.S. CNET will post its review later Friday, so check back for our impressions of the device. If you're thinking about buying one, here's some stuff you should know ahead of time:

Standing in line
It's become a tradition for some hardcore types to stand in line, sometimes days in advance, to be one of the first to get the latest iPhone. There may not be a need to start queuing quite that early this time around, however. That's because for the iPad, Apple allowed the option to reserve one of the new touchscreen tablets ahead of time, so as long as you pick it up by 3 p.m. Saturday (that's how long they've guaranteed to hold the reservation), you'll get one the first day.

What's unclear is if there will be supply of iPads set aside for walk-in customers. Apple says there will be two lines: one for people who placed a pre-order via the Web (an option that is no longer available), and one that will be first-come, first serve. Though Apple will not say how many iPads will be available to sell to people who have not pre-ordered, it does sound like there will be stock for people to simply walk in and buy one.

Wi-Fi versus 3G
Though Apple has announced there will be two models of the iPad, one won't be available at first. The Wi-Fi-only version of the iPad will be for sale starting Saturday. A different model, which will have Wi-Fi and 3G access, won't be ready until late April.

But you still have some options. The Wi-Fi model comes in three different storage capacities: 16GB of memory for $499, 32GB for $599, and 64GB for $699. Buying the 3G version tacks $129 on to each.

Accessorizing
One of the interesting things about the iPad is the accessories. Unfortunately, some of them won't be available right out of the gate. The accessory most likely to inspire envy among iPhone owners--the iPad keyboard dock--is delayed until May. The same is true for the 10W USB power adapter that will charge the iPad from an electrical outlet. The iPad case is available in mid-April-but if you search around there are plenty more options from third-party vendors should you want one right away.

The camera-connector kit will be available in late April, and the iPad Dock Connector to VGA Adapter will be in stock Saturday.

What it's for?
The iPad isn't a phone, and it's not exactly a computer. So what is it? It's a touchscreen device for consuming media in all its forms: video, music, the Web, electronic books and magazines, and video games.

There's also work-related things you can do with it: create presentations, spreadsheets, documents through the iWorks applications Apple will make available via the App Store. Plus there's all the usual trappings of a computer or smartphone: email, calendars, contacts, maps, and of course, access to the iTunes Store and App Store. This is all accomplished with the swipe of your fingers, since there's no physical keyboard or stylus included. That is, unless you connect it to the keyboard dock or a wireless Bluetooth keyboard.

Books will be an initial focus of the device. Apple has said its iBooks app will feature e-books from five major publishers: HarperCollins, Hachette, Penguin, Macmillan, and Simon & Shuster at first. Magazine and newspaper publishers are also expected to flock to the device. So far, the New York Times and Wired Magazine have demonstrated iPad-friendly applications.

What you can't do with the iPad: take photos. So far, there's no Web cam on the iPad. That could change one day, but for now, you can only get photos onto it via a dock connector Apple sells or by emailing them to yourself and downloading them to the iPad.

You also can't edit Microsoft Word documents or watch Flash videos. That means you won't be able to watch Hulu, but you also won't be subjected to some of those irritating Flash-based ads on Web sites.

Apptastic
One of the most attractive features of the iPad is its relatively large screen (9.7 inches) compared to the iPhone and iPod Touch (3.2 inches). For iPad owners, that means the apps they know and love from the iPhone will be displayed even bigger and perhaps better. On Thursday Apple started updating the App Store with the first round of iPad apps.

Apple has said that all the apps in the App Store, which now number over 150,000, will work right away on the iPad. This is accurate, but there are two things to keep in mind: First, an iPhone app you already own, say the Facebook app, will run on the iPad as is. But it's going to be centered on the screen at its original iPhone scale. No one really will want that though, so Apple has included a "2x" button that will automatically scale the app to fit the iPad's screen.

For some apps, that's no problem, they'll look fine. But others, like games for instance, will look pixelated. For that reason, many app developers are retooling their apps and selling them as "HD," "XL," or "for iPad." And yes, in some cases this will mean they cost more money. Bigger applications versus more time spent? It does make sense.

Other helpful tips for getting started
Though you don't need a computer to use the iPad most of the time, you will need one with iTunes 9.0 or later to set up the device initially. To use the iPad at home (if you don't have the 3G model) you'll also need to have a home wireless network. And if you want to utilize the iPad as a photo frame, you'll have to pick up the charging dock.

Unfinished product
Though the iPad will go on sale Saturday, we haven't seen it in its final form. Of course, there will be upgrades as memory gets cheaper, and technology progresses, but the evolving software is what is likely to really define the device.

It's likely there are still some pretty big announcements to come as Apple works out more content deals. Part of that might hinge on the initial public response to the device: if publishers see this is a viable format, more or likely to climb on board. Things we hope to see include the ability to access our music collections from the cloud, streaming videos, maybe even iTunes Store subscriptions to TV shows, more access to college textbooks, magazine subscriptions, and new ways to read the newspaper.