Visual Studio 2010 SP1 (not beta version) was released in March 03, 2011, but this date is from Microsoft Official site, other websites gave the release date is March 10, 2011.
Now you can download from Microsoft Official site here.
The downloading time was very fast, but the installing time was long, because you just downloaded a starter tool, every files are located online.
The following is our installing process:
4: start the long time installing process now ...
5: Finally, After about 1 hour installing (the computer information attached below), You can see the finish window:
Interl Core 2 Duo CPU T5850 2.16GHz 3G RAM Windows XP Pro Dell Laptop Studio 1510
6: Then, you have to restart your computer: