Rather than make a new post I guess I can tack it on here. What Chaintm said is correct, if you pre-order through impulse you get access to the beta through there you just have to set it to show pre-release. Having just pre-ordered and done that I've run into the brick wall of the download failing completely. Gets to about 7 percent and then fails a verification check. Error log gives this as the reason...
-- [7/26/2010 9:35:31 PM] ----------------------------------------------------
Context: General
Message: MD5 ERRORS: Verification FAILED for piece #1 of 14 in 'C:\Documents and Settings\All Users\Application Data\Stardock\Impulse\Temporary\DownloadQueue\elemental\elemental0.92[b].081.impulse'. (MD5-Expected: bac817be9b5a5308028857d41a7ba211, MD5-Observed: e7bb802b924834dd7b3d3e0f8d1a2222, PieceSize: 104857600, Observed range: 0x00000000-0x063fffff)
Build #: 1982
-- [7/26/2010 9:35:31 PM] ----------------------------------------------------
Context: General
Message: MD5 ERRORS: Trimming file 'C:\Documents and Settings\All Users\Application Data\Stardock\Impulse\Temporary\DownloadQueue\elemental\elemental0.92[b].081.impulse' down to byte offset 0x00000000
Build #: 1982
Multiple tries end in the same result.