After an early misfire, Microsoft officially opened pre-orders for some of its Surface tablets Tuesday, finally announcing a price months after unveiling the devices in June.

Pre-orders for the Surface tablet with Windows RT — a lighter version of the full Windows operating system — opened at noon Eastern on Microsoft's Web site. Here’s what you need to know about the pre-orders:

What’s the price: The Surface with Windows RT starts at $499 for the 32 GB version. Add the keyboard touch cover accessory and the cost goes up to $599. For the $699 64 GB version, Microsoft will include the touch keyboard at no extra cost. They run on WiFi networks.

Microsoft has yet to release the pricing of the 32 GB and 64GB Surface with Windows 8 Pro tablets that run a full version of Windows 8’s professional edition.

Accessories: If you want a touch keyboard cover that isn’t black you’ll have to spring for it separately. The covers come in black, white, red, cyan and magenta and will cost you $119.99, And if you want the type cover, which is essentially a super-thin keyboard with full keys, it’ll cost you $129.99.

How to buy one: If you want the Surface with Windows RT, you can pre-order it Microsoft’s Web site for delivery by the Oct. 26 launch date. You can, of course, also wait until the devices show up at Microsoft stores in the United States and Canada on the same day. The tablet will be online in six more markets Friday: Australia, China, France, Germany, Hong Kong and Britain.

How to choose between models: Not sure if you should buy the Surface with Windows RT now or wait for the Pro version? There are some key differences between the tablets that you should consider — particularly if you’re thinking about using the tablet for work.

The RT tablet won’t have a couple of features that will be available on the full-Windows tablet, including Windows Media Player, Windows Media Center and Remote Desktop. It will, however, have the capability to turn on instantly and update more quickly than the Pro tablet.

There also are some physical differences between the tablets. The RT version is a half-pound lighter and 4 mm thinner than the Pro version. It also has USB 2.0 ports instead of USB 3.0 ports and an HD video out port instead of a mini display port. The Pro version has a longer battery life than the RT tablet.

The two tablets also run different versions of Office, customized for each system.

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