mekyle99 :
Just did a plug and go. Another thing worth mentioning is that it wasn't me who did the upgrade, it was my local PC store.
That's going to be it right there. You likely have a bunch of driver conflicts going on and, while they may not be causing crashes/BSODs currently, it's never going to feel as "smooth" as a clean install.
I'm [strike]shocked[/strike] disappointed a PC store would actually let that happen.