Heh .. buy a new motherboard and a new intel CPU. You may need to replace your OS as well because when you change out motherboards .. you usually have to buy a new OS to go along with it depending on your version of windows. If I were you I'd upgrade to a Phenom II 720 or a similar chip and you'll still get very good speeds for a LOT less money. Especially going from a 9500 to that. You could also go for a Phenom II 940 and get extreme benefits over that CPU. The original phneom series chips were crap. Sorry to say yours in particular was a real dud performance-wise.
Intel processors run on different sockets and motherboards, so you'll need to purchase a new motherboard. Usually to prevent system instability you also need to reinstall windows when changing motherboards, plus having a gateway, it may force you to reinstall it or won't even run. Than because gateway would of used a proprietary version of windows, they won't let you install it on different hardware so you'll need to purchase a new copy of windows as well.
You're going to need a new motherboard and maybe new RAM if you plan on switching. All in all, if a Core i5 or i7 is what you want, it'll probably end up costing you anywhere between $400 (and that's being generous) and $600 (for a damn good machine).
When you change from an AMD socket motherboard to an Intel socket motherboard, you are changing northbridge and southbridge chipsets. Even if you uninstall the old chipset drivers, Windows probably won't allow a successful repair, and will need to be re-installed, as has been mentioned. Therefore, the very first step is to backup anything you wish to retain, prior to changing your hardware.