Windows 8 can be downloaded from almost anywhere but not everyone has the time or the will to check if they are indeed original, untouched images just like the ones from Microsoft MSDN.
I have compiled a list of the file names and hashes for the English and Spanish versions so you can check them against the files you downloaded to make sure you are getting an original Microsoft image and not one that was tampered with or altered in some way. I have also included the file names and hashes for the language packs that are already available in case you need to compare them.
To check the file hashes, you can use HashTab, my favorite file hasher. You can download my custom installer.
Install it, right click or your ISO image and click on the File hashes tab. It will calculate the hash and give you a text box to paste a hash code to compare it against that file. Easy.
Operative System
WINDOWS 8 CORE/PRO X86
File Name: en_windows_8_x86_dvd_915417.iso
SHA1: 22D680EC53336BEE8A5B276A972CEBA104787F62
WINDOWS 8 CORE/PRO X64
File Name: en_windows_8_x64_dvd_915440.iso
SHA1: 1CE53AD5F60419CF04A715CF3233F247E48BEEC4
WINDOWS 8 ENTERPRISE X86
File Name: en_windows_8_enterprise_x86_dvd_917587.iso
SHA1: FEFCE3E64FB9EC1CC7977165328890CCC9A10656
WINDOWS 8 ENTERPRISE X64
File Name: en_windows_8_enterprise_x64_dvd_917522.iso
SHA1: 4EADFE83E736621234C63E8465986F0AF6AA3C82
WINDOWS 8 PRO VL X86
File Name: en_windows_8_pro_vl_x86_dvd_917830.iso
SHA1: 548AB51161FD83B889596B143D86C1EEB61EF2D0
WINDOWS 8 PRO VL X64
File Name: en_windows_8_pro_vl_x64_dvd_917699.iso
SHA1: 6DDEDEBE40AB59CB11823F62F475C43C4053FE60
WINDOWS 8 CORE/PRO X86
File Name: es_windows_8_x86_dvd__915471.iso
SHA1: EDFD8D6B7D427953A7A90AD44D8828273F62EE01
WINDOWS 8 CORE/PRO X64
File Name: es_windows_8_x64_dvd_915404.iso
SHA1: 73721BF958C9237165AED00E41EABAE492915E0B
WINDOWS 8 ENTERPRISE X86
File Name: es_windows_8_enterprise_x86_dvd_917591.iso
SHA1: B319C5C23047E280B334BC159B6B785942ACB87B
WINDOWS 8 ENTERPRISE X64
File Name: es_windows_8_enterprise_x64_dvd_917926.iso
SHA1: B3249287E9424C1D02519C4440EDAC262138274F
WINDOWS 8 PRO VL X86
File Name: es_windows_8_pro_vl_x86_dvd_917834.iso
SHA1: 33741CC03C8FB4BCD0937CE1EC156FFE05B17C02
WINDOWS 8 PRO VL X64
File Name: es_windows_8_pro_vl_x64_dvd_922088.iso
SHA1: 169AEC2237EE3B7AF7EB2A6786A54AF3BE7D7704
Language Packs
WINDOWS 8 LANGUAGE PACK X86
File Name: mu_windows_8_language_pack_x86_dvd_917546.iso
Languages: English, Japanese, Arabic, Bulgarian, Czech, Danish, German, Greek, Spanish, Estonian, Finnish, French, Hebrew, Croatian, Hungarian, Italian, Lithuanian, Latvian, Dutch, Norwegian, Polish, Portuguese-Brazil, Romanian, Russian, Slovak, Slovenian, Serbian, Swedish, Thai, Turkish, Ukrainian, Multi-Language, Chinese – Hong Kong SAR, Chinese – Taiwan, Chinese – Simplified, Portuguese-Portugal, Kyrgyz
SHA1: F8734AF3D58AC80F8455857F65108F3F585F18AE
WINDOWS 8 LANGUAGE PACK X64
File Name: mu_windows_8_language_pack_x64_dvd_917544.iso
Languages: English, Japanese, Arabic, Bulgarian, Czech, Danish, German, Greek, Spanish, Estonian, Finnish, French, Hebrew, Croatian, Hungarian, Italian, Lithuanian, Latvian, Dutch, Norwegian, Polish, Portuguese-Brazil, Romanian, Russian, Slovak, Slovenian, Serbian, Swedish, Thai, Turkish, Ukrainian, Multi-Language, Chinese – Hong Kong SAR, Chinese – Taiwan, Chinese – Simplified, Portuguese-Portugal, Kyrgyz
SHA1: 5A79DC188F8368D8A285D75075E194D15B126929
With this file names and hashes you at can be sure that the images you download are unmodified.
For a detailed explanation of all the Windows 8 editions, you can check this Wikipedia article.