When downloading SBS Essentials from the eval site you might want to run a Sha1 test to make sure that the download is a good download.
SHA1: 58FE96CD15B46107C0030713CB75A18B5FAFEF69 ISO/CRC: 1345F2EF
Z:\>fciv en-us_sbs_ESS_eval_installdvd.iso -sha1
// File Checksum Integrity Verifier version 2.05.
664d2d01564070f11699bcc219fbe4ad48866d99 en-us_sbs_ess_eval_installdvd.iso Is the Sha1 I received. The MD5 was d96ad518b35fb02e67b728d988007ea8 en-us_sbs_ess_eval_installdvd.iso
One interesting recent kb that may impact you when to try to install the server is this one:
Who knew that uppercase and lowercase mattered.