Get a Dropbox account - they're free for up to 2 Gbyte of storage. Then, drop your epubs (or whatever) into dropbox on your PC (or Mac) and sync with your IPad (download Dropbox for free from the App Store).

Dropbox will automatically offer to load the epubs into whatever ebook reading app that is on your IPad - couldn't be any simpler.

Calibre becomes a PITA to use after a while.