I want to hide my IP address on my PC but dont want to go through all the suggestions I have received. IF i was to use my laptop computer and use a dongle and set up an account on Yahoo or gmail would my IP address be different from the one on my PC?
Yahoo and/or Gmail aren't going to change your IP. If you're talking about email headers, we've discussed that on the site here.
If you use a "dongle", meaning a USB wired or wireless NIC, that NIC would have a different MAC address as your PC and will pull a different IP than your on-board NIC. If you're sharing a connection behind a router, then you'll still see the same IP on whatismyip.com.