Q: Has anyone had difficulty transfering itunes to a computer using Windows 8?

Hello, Copper Penny. 

Thank you for visiting Apple Support Communities. 

The most common cause for missing media upon transferring to a new computer is the media folder is not located where iTunes can locate the files.  Here are a couple articles that will help you locate the missing media.

iTunes: Finding lost media and downloads

http://support.apple.com/kb/TS1408

iTunes: How to move your music to a new computer

http://support.apple.com/kb/HT4527

Also, you can download your past purchases at any time free of charge by following the steps below. 

Downloading past purchases from the App Store, iBookstore, and iTunes Store

http://support.apple.com/kb/HT2519

Cheers,

Jason H.