there are several ways.
MS offers Windows 7 ISOs through their DigitalRiver servers: http://superuser.com...-from-Microsoft
They do not have something similar for Windows 8 but if one searches hard enough you can find direct links from MS.
Another LEGAL way is to use the Windows 8 Upgrade assistant.
It will allow you to download and save an ISO to your PC provided that you have a serial for Windows 8.http://www.intowindo...ng-product-key/
You will still be able to download windows 8 if you do not have your key on you by inputting the standard key that is bound to all windows ISOs. (this will not activate but will allow you to just download it through Windows 8 Upgrade assistant: XKY4K-2NRWR-8F6P2-448RF-CRYQH
Some more installation/download keys for the different SKUs: http://www.microsoft...dows-8-adk.aspx
Note: If you do get your copy from not so official sources then make sure to verify the hash tags against the official ISOs which can be found here:http://msdn.microsof...ndex=0&FileId=0
This will ensure that the image hasn't been tampered with.
Sorry InsaneNutter .. no direct links since they are not on DigitalRiver. But I think the Upgrade Assistant is a really nice and easy way. The only disadvantage might be that it wont download ISOs if you go from x86 to x64 but I am honestly not sure.