MAKING IPHONE / IPAD BACKUPS WITH ITUNES to PC

I will occasionally plug my iphone and ipad into my PC and make a full backup using Itunes on Windows. The file created is huge. I need to save it an external drive and not on my pc. Can I set a new destination drive that is not on my c or d drive? Also I do sync to icloud everyday, is there a way to make incremental saves to the PC as well?