Engadget has discovered a series of new smartphones from Dell that are as appealing on the inside as they are on the outside.

We will start with the Lightning -- a gorgeous portrait slider that's poised to compete well with Windows Phone 7 devices.

Underneath the hood we find a 1GHz QSD8250 Snapdragon processor, a huge WVGA 4.1-inch OLED display, a 5-megapixel auto-focus camera, 1GB of flash memory with 512MB of RAM, 8GB of storage on a microSD, Adobe Flash support (won't be available at launch), GPS, an accelerometer, a compass, and FM radio -- all on a phone compatible with AT&T and T-Mobile 3G. Word is that it might even get an upgrade to LTE in Q4 of 2011.

The Lightning is expected to be among the first batch of Windows Phone 7 devices launching in Q4 of 2010.

Moving on, we have the Thunder, which is the Android component of Dell's Thunder and Lightning one-two punch.

Details are on the light side, but the Thunder will include Android 2.1 with Dell's customized "Stage" UI on top, a 4.1-inch WVGA OLED screen, deep social networking integration, Adobe Flash support and, possibly, an integrated Hulu video app. The rest of the specs aren't available, but we would expect it to be similar to the Lightning. There is also talk of an 8-megapixel camera.

The Thunder is expected in Q4 of this year as well, and it will seeming launch on AT&T with an LTE model planned for the end of 2011.

Both the Lighting and the Tunder are pictured above in the right-hand column.

The Flash and Smoke both run on Android Froyo with 800MHz Qualcomm MSM7230 processors, and offer 14.4Mbps HSPA alongside a 5-megapixel camera.

The Flash will also include a 3.5-inch WVGA LCD, 12MB of RAM and ROM with microSD expansion up to 64GB (assuming there are 64MB microSD cards next year), Wi-Fi, TV-out, Bluetooth 3.0 and a design fashioned out of "curved glass."

The Smoke is aimed at the corporate set with features like a 2.8-inch QVGA display, microSD expansion up to 32GB, QWERTY keyboard, Wi-Fi, Bluetooth 2.1 + EDR, and dual-mic noise canceling. Supposedly, the price "won't break the bank".

Expect the Flash in Q1 of 2011 on AT&T and the Smoke to follow in Q2.