Last week, some details were leaked in the wild that Microsoft sent invitations to a selected pool of Technical Beta testers, to inform them of the availability of Windows 7 Service Pack 1 Beta and Windows Server 2008 R2 SP1 Beta for testing. Now it seems, Microsoft has started delivering the Beta bits to them.

Sources say, The build number of the first Beta  is 7601.16562.100603-1800 that means that the build was compiled on June 3rd, 2010 weighing 1.22GB.

For your information, Service Pack 1 for Windows 7 and Windows Server 2008 R2 comes as joint release and its is not major release for Windows 7. It includes only minor updates that are already delivered through Windows Update since Windows 7 RTM Build 7600. However an updated Remote Desktop Client will be introduced that takes advantage of RemoteFX introduced for Windows Server 2008 R2 SP1.

For Windows Server 2008 R2, two new desktop virtualization features will be introduced with SP1.

• Microsoft RemoteFX and
• Dynamic Memory

These features are designed to extend utilization of virtualization with Windows Server 2008 R2.

Microsoft revealed its plans for Windows 7 SP1 and Windows Server 2008 R2 SP1 earlier this month at Tech-Ed conference that they are planning to release a public beta by the end of July.