Microsoft has announced that a beta version of their upcoming free antivirus software, Microsoft Security Essentials (MSE), will be released June 23. The application will provide real-time protection against viruses, spyware, trojans and rootkits. Up until Tuesday when the pre-beta version leaked, it had only been touched by the hands of Microsoft employees and select testers.

The coming beta will be publicly available to 75,000 users which speak English and Portuguese. It will come as a 32 and 64-bit standalone installer for Windows XP, Vista and 7 users. Redmond says that 75k is a target figure and they’ll consider an increase if necessary. Following the initial beta, Microsoft plans to launch a Beta Refresh or possibly even a Release Candidate over the summer. The finished product is expected to arrive by Windows 7’s release date of October 22.

MSE appears to be pretty lightweight and has modest system requirements. Installed, it consumes about 11MB of space and requests that 140MB of additional hard drive space is available. For XP users it is recommended to have a CPU with a clock speed of at least 500MHz and a minimum of 256MB of RAM. Vista and 7 users are suggested to have a 1GHz CPU and 1GB of RAM.