Amazon Germany already lists five models of Microsoft's recently announced Surface tablet PC, the software giant's first foray into the competitive tablet market. The five models listed include a smaller 32GB version that had not been announced. Amazon lists no price or release dates on the Surface product pages. Instead, users are simply directed to sign up via email in order to be notified when the tablets become available.

Four of Microsoft's 10.6-inch tablets uncovered on the German forum NetzwerkTotal match the models unveiled during the software giant's Surface announcement. These models also match the specs sheet available on Microsoft's Surface Web site. The fifth model listed on Amazon, however, comes as a surprise.

The models listed include two Windows 8 Pro Surface tablets - one with 64GB of flash memory and one with 128GB. These are the more powerful models, sporting Intel Core i5 Ivy Bridge processors, as well as the full version of the new Windows 8 software. The Surface Pro models are also expected to cost more than typical tablets, falling more in line with ultrabook prices. Ultrabooks are the main challenge for Microsoft's Surface Pro.

The other two of the four announced tablets are Surface RT models with Nvidia Tegra 3 quad-core processors - one with 32GB of memory and the other with 64GB. As previously mentioned, Amazon Germany has also listed a surprise model: a 32GB Surface Pro, presumably with similar hardware features such as full HD display, USB 3.0, stylus pen support, and a 42 watt-hour battery. This 32GB model is expected to be a cheaper, entry-level version to compete with laptops and ultrabooks.

Again, there is no official word on pricing yet, but sources close to Microsoft told The Next Web that the Surface Pro will start at $999, while the Surface RT would start at $599. Should these prices prove to be accurate, the 64GB Surface Pro model would actually cost several hundred dollars more than some of the most recently announced ultrabooks, which range in price from $599 to $799.

Amazon Germany does not list more detailed specs for the Surface RT tablets, but previous reports indicated these devices will come as the thinner and lighter versions running the tablet-optimized version of Microsoft's latest operating system, Windows 8.