It's running Windows XP Home SP3 out of the box. The heart of the device is Intel's N270 [aka ATOM] 1.6Ghz processor which runs the OS without hiccup so far. Remember though that my system has 2Gb of RAM and 160Gb HDD. A note on the HDD: mine came with 3 partitions -- 40 OS / 110 Storage / 10 Hidden for OS. I like the fact that it is not the anemic SSDs which are usually loaded in some mini/netbooks. The notebook also has WiFi and Bluetooth, a card reader, and a webcam. The power brick is tiny as well.
I'd like to say that the build quality on this MSI is really really nice. The screen is bright and crisp. Typing on the keyboard is comfortable and not really a strain for me. If I do have a complaint it would be the single unit design of the key bellow the track pad. It is really hard to press and register a click. One can easily add a usb mouse, rf or bt mouse though. Overall I am not missing the media drive at the moment, I guess I don't really use it that much even on my desktop. I'd probably get an external media drive as the need arises. The sound on this is actually all right for indoors/office use but I reckon you'd need earphones at a noisy coffee shop. I got the 3cell battery with my Wind, I would've liked a 6cell battery but it wasn't available yet.
I am currently installing Windows Updates and my most commonly used apps. I don't think all my media will fit my storage partition so they'll probably stay on my office desk. Right now I have the apps I use on a daily basis. I guess I will add more as I use the notebook.
I plan to pair some Bluetooth devices to the Wind tonight and if time permits maybe test the webcam/mic as well. By the way I am typing this post up on the Wind's keyboard and I should say it is not as painfully difficult as I thought it would be. I am getting good response from the keys and a few typos. YMMV.